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                                                                    EXHIBIT 10.5

                               MUTUAL CONTRIBUTION
                   AND ENVIRONMENTAL INDEMNIFICATION AGREEMENT

This MUTUAL CONTRIBUTION AND ENVIRONMENTAL INDEMNIFICATION AGREEMENT, dated as
of September 10, 2004, is entered into by and among, on one side, Toshiba
Corporation, a Japanese corporation ("Toshiba"), and, on the other side, SANDISK
CORPORATION, a Delaware corporation, and SanDisk International Limited, a
company organized under the laws of the Cayman Islands ("SanDisk International",
and collectively with SanDisk Corporation, "SanDisk," and SanDisk together with
Toshiba, the "Parties").

                                    RECITALS

      WHEREAS, Toshiba and SanDisk are parties to that certain Flash Partners
Master Agreement, dated as of the date hereof (the "Master Agreement");

      WHEREAS, pursuant to the terms of the Master Agreement and other Operative
Documents, Flash Partners Y.K., a Japanese yugen kaisha (the "Company"), will
have Y3 NAND Flash Memory Products manufactured at the Y3 Facility; and

      WHEREAS, Toshiba and SanDisk have agreed to mutually contribute to, and
indemnify each other and the Company for, environmental remediation costs or
liability resulting from such manufacturing operations as set forth below.

      NOW, THEREFORE, the Parties agree as follows:

1.    DEFINITIONS AND INTERPRETATION.

1.1   Master Agreement. Appendix A to the Master Agreement is hereby
      incorporated into this Agreement. Capitalized terms used but not defined
      in this Agreement shall have the meanings given to them in Appendix A.

1.2   Definitions. The following terms used in this Agreement shall have the
      following respective meanings:

(a)   "Environmental Laws" means all Applicable Laws in Japan, including, but
      not limited to, the Soil Contamination Control Law (Dojyouosen Taisaku Ho,
      Law No. 53 of 2002), now or hereafter in effect relating to the protection
      of human health, safety, and the environment from emissions, discharges,
      releases or threatened releases of pollutants, contaminants (chemical or
      industrial), toxic or Hazardous Substances or wastes into the environment
      (including, ambient air, soil, surface water, ground water, wetlands, land
      or subsurface strata), or otherwise relating to the manufacture,
      processing, distribution, use, treatment, storage, disposal, transport or
      handling or investigation or remediation of pollutants, contaminants,
      chemicals or industrial, toxic or hazardous substances or wastes.

(b)   "Hazardous Substances" means petroleum, petroleum hydrocarbons or
      petroleum products, petroleum by-products, radioactive materials, asbestos
      or asbestos-containing

CERTAIN INFORMATION IN THIS EXHIBIT HAS BEEN OMITTED AND FILED SEPARATELY WITH
THE COMMISSION. CONFIDENTIAL TREATMENT HAS BEEN REQUESTED WITH RESPECT TO THE
OMITTED PORTIONS.

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      materials, gasoline, diesel fuel, pesticides, radon, urea formaldehyde,
      lead or lead-containing materials, polychlorinated biphenyls; and any
      other chemicals, materials, substances or wastes in any amount or
      concentration which are now or hereafter become defined as or included in
      the definition of "hazardous substances," "hazardous materials,"
      "hazardous wastes," "extremely hazardous wastes," "restricted hazardous
      wastes," "toxic substances," "toxic pollutants," "pollutants," "regulated
      substances," "solid wastes," or "contaminants" or words of similar import,
      under any Environmental Law.

2.    ENVIRONMENTAL INVESTIGATIONS.

2.1   Environmental Consultants. The Parties acknowledge that each of SanDisk
      and Toshiba has engaged an environmental consulting company to conduct an
      environmental investigation on its behalf as to the surface and subsurface
      conditions existing on the proposed site of the Y3 Facility (each a
      "Consultant" and the Consultant engaged by SanDisk, the "SanDisk
      Consultant" and the Consultant engaged by Toshiba (the "Toshiba
      Consultant"). SanDisk shall be solely responsible for the fees and costs
      charged by the SanDisk Consultant and shall indemnify and hold harmless
      Toshiba and the Company from any claims for compensation or damages made
      by the SanDisk Consultant. Toshiba shall be solely responsible for the
      fees and costs charged by the Toshiba Consultant and shall indemnify and
      hold harmless SanDisk and the Company from any claims for compensation or
      damages made by the Toshiba Consultant; provided, however, that fees and
      costs incurred by the Toshiba Consultant after the Closing and other than
      in connection with finalizing the Baseline Environmental Report (as
      defined below) shall be chargeable to and payable by the Company, which
      fees and costs shall be chargeable to and payable by the Parties through
      wafer price increases.

2.2   Scope of Review. Each Consultant has performed the activities customarily
      associated with Phase I (tochirireki chosa) and Phase II (osen jokyo
      kakunin chosa) studies. Such activities were performed at the Y3 Facility
      and elsewhere at the Yokkaichi Facility as identified in the Toshiba
      Consultant's reports and the SanDisk Consultant's reports; provided,
      however, that the Parties acknowledge that due to construction activities
      at the Y3 Facility the SanDisk Consultant was not permitted to obtain soil
      or water samples from those areas identified on Exhibit A (such areas, the
      "Untested Areas").

2.3   Information from Monitoring Activities. Toshiba shall share, or cause to
      be shared, with SanDisk and, upon SanDisk's request, the SanDisk
      Consultant, the results of any monitoring activities conducted by Toshiba
      or its Affiliates with respect to the surface and subsurface conditions on
      the site of the Y3 Facility on or after the Effective Date and until the
      FP Termination Date; provided that if as of the FP Termination Date any
      claims have been made against SanDisk with respect to its indemnification
      obligations hereunder, on SanDisk's request, Toshiba shall continue to
      provide SanDisk the results of any monitoring activities to the extent
      such results may affect the evaluation or determination of alleged
      liability of SanDisk hereunder. The Parties acknowledge and agree that any
      such information concerning the Y3 Facility shall be considered
      Confidential Information of the Company and any such information
      concerning the

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      Yokkaichi Facility (including the Y3 Facility) shall be considered
      Confidential Information of Toshiba.

3.    BASELINE ENVIRONMENTAL REPORT.

      Each Party shall direct the Consultant retained by it to (i) provide the
      other Consultant and other Party with its initial environmental report on
      the Y3 Facility and (ii) discuss the reports in good faith with the other
      Consultant with the intent of the Parties and their Consultants agreeing
      upon a single, combined report (the "Baseline Environmental Report"). If
      Toshiba, SanDisk and the Consultants are unable to agree upon a single
      report within sixty (60) days after the Closing, then the draft reports of
      both Consultants (or combined report indicating areas of disagreement)
      shall collectively be considered to be the Baseline Environmental Report.

4.    ENVIRONMENTAL COMPLIANCE.

4.1   The Parties confirm their intent that the Y3 Facility and all operations
      of the Company be maintained in compliance with all Environmental Laws,
      including by having remedial measures taken as required by any
      Governmental Authority or otherwise reasonably necessary to ensure that
      the Y3 Facility and all operations of the Company will remain in
      compliance with all Environmental Laws.

4.2   Each Party shall promptly notify the other of any circumstances of which
      it becomes aware that require or could reasonably be expected to require
      remediation or other actions to ensure that the Company and its operations
      are and will be maintained in compliance with all Environmental Laws and
      to minimize the aggregate Covered Environmental Costs (as defined below)
      that may be incurred. Upon any such notice being given and received, the
      Parties shall promptly discuss in good faith and seek to agree upon the
      measures to be taken in response to such circumstances. Pending their
      agreement, nothing shall prevent or limit Toshiba, acting in good faith on
      its own initiative or upon SanDisk's reasonable request, from
      investigating the circumstances of any releases of Hazardous Substances or
      taking steps reasonably appropriate to limit or prevent ongoing releases,
      to limit the effects of a release, or to prevent or limit any exposure or
      damage resulting from, arising out of or otherwise by virtue of a release,
      including taking immediate or urgent steps as appropriate in light of the
      circumstances then known, provided, that nothing in this paragraph shall
      require either Party to take any step except as required by applicable
      Environmental Law.

5.    INDEMNIFICATION OBLIGATIONS.

5.1   Mutual Responsibility and Indemnity for Environmental Costs.

(a)   Subject to Section 5.1(b), each of SanDisk and Toshiba shall:

      (1)   be responsible for bearing 50% of all costs, expenses or liability
            (including claims by third parties or any Governmental Authority)
            resulting from any contamination from the release or discharge of
            Hazardous Substances resulting from, arising out

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            of or otherwise by virtue of the operation of the Y3 Facility from
            the Closing until the FP Termination Date, including any and all
            costs to investigate, remove or remediate any release of Hazardous
            Substances or otherwise reasonably necessary to assure that the
            Company and the Y3 Facility are and will (until the FP Termination
            Date) remain in compliance with then applicable Environmental Laws
            ("Environmental Costs"); and

      (2)   indemnify, defend and hold harmless the other Party and the Company
            (and their respective Indemnified Parties) for its 50% share of all
            Environmental Costs.

(b)   Each of SanDisk's and Toshiba's responsibility for 50% of Environmental
      Costs under Section 5.1(a) shall be subject to each of the following
      limitations (Environmental Costs not excluded from the one or both
      Parties' responsibility under this Section 5.1(b), "Covered Environmental
      Costs"):

      (1)   Except as provided in Section 5.2(a), neither Party shall be
            responsible for conditions identified in the Baseline Environmental
            Report, including responsibility for any Environmental Costs
            resulting from, arising out of or otherwise by virtue of remediation
            or removal of pre-existing conditions. However, if remedial measures
            otherwise taken in accordance with this Agreement incidentally
            result in remediation or removal of conditions not resulting from
            operation of the Y3 Facility, only the Environmental Costs paid for
            the remedial measures taken with respect to the Y3 Facility
            (including amounts paid for remedial measures taken with respect to
            the Y3 Facility that return the Y3 Facility to a condition better
            than that identified in the Baseline Environmental Report) shall
            constitute Covered Environmental Costs.

      (2)   Neither Party shall be responsible for Environmental Costs to the
            extent such Environmental Costs are incurred as a result of the
            willful misconduct of employees, agents or representatives of the
            other Party.

      (3)   Environmental Costs incurred for remediation shall only constitute
            Covered Environmental Costs to the extent reasonably necessary to
            ensure that the Company fulfills the Prudent Operator Standard. The
            "Prudent Operator Standard" means taking all such remedial measures
            (i) as are required to be in compliance with all then effective
            Environmental Laws, (ii) that have been required by a Governmental
            Authority or (iii) that a prudent operator of a similar facility
            would then take or begin to take to ensure that its continuing
            operations and facilities will remain in compliance with then
            effective Environmental Laws and with Environmental Laws as they are
            then scheduled to go into effect or are anticipated to be changed in
            the next [***].

      (4)   No Environmental Costs shall constitute Covered Environmental Costs
            with respect to either Party to the extent such Party's liability
            limit under Section 5.5 has been exceeded.

[***] INDICATES THAT CERTAIN INFORMATION ON THIS PAGE HAS BEEN OMITTED AND FILED
SEPARATELY WITH THE COMMISSION PURSUANT TO RULE 24B-2. CONFIDENTIAL TREATMENT
HAS BEEN REQUESTED WITH RESPECT TO THE OMITTED PORTIONS.

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(c)   If the Parties are not able to agree on whether any given Environmental
      Costs constitute Covered Environmental Costs (including whether
      remediation is necessary to fulfill the Prudent Operator Standard, such
      dispute shall be resolved by the mediation and arbitration provisions of
      Appendix A.

5.2   Toshiba Indemnity. Toshiba shall indemnify SanDisk and its Indemnified
      Parties from any environmental costs, expenses or liabilities of SanDisk
      resulting from, arising out of or otherwise by virtue of:

(a)   environmental conditions existing at the Yokkaichi Facility, including the
      Y3 Facility, prior to the Closing;

(b)   the actions or omissions of Toshiba, its Affiliates or its or their
      respective employees, directors, agents or representatives (other than in
      connection with the operation of the Y3 Facility), for which Toshiba shall
      be solely responsible; provided however, that Toshiba shall have no
      indemnification obligation under this Section 5.2(b) to the extent that
      any Environmental Costs result from, arise out of or otherwise occur by
      virtue of actions or omissions of SanDisk, its Affiliates or its or their
      respective employees, directors, agents or representatives, for which
      SanDisk shall be solely responsible; or

(c)   from the operations of the Y3 Facility after the FP Termination Date
      (unless SanDisk is the Buyer for purposes of Section 5.3, in which case
      this Section 5.2(c) shall not apply).

5.3   Buyer Indemnity. If either of Toshiba or SanDisk (as "Buyer") acquires the
      interests of the other (as "Seller") in the Company and the Y3 Facility
      (whether through acquiring its Units in the Company, by an asset sale and
      liquidation or by other means), then, subject to Section 7, Buyer shall
      indemnify Seller and its Indemnified Parties from any environmental costs,
      expenses or liability of Seller resulting from, arising out of or
      otherwise by virtue of, operations of the Y3 Facility after the FP
      Termination Date. However, Buyer shall have no indemnification obligation
      under this Section 5.3 to the extent that any Seller environmental costs,
      expenses or liabilities result from, arise out of or otherwise by virtue
      of actions or omissions of Seller, its Affiliates or its or their
      respective employees, directors, agents or representatives.

5.4   Control by Indemnifying Party.

(a)   The indemnifying Party under Section 5.2 or 5.3 shall have the sole right
      to control the defense of any claim and the method and scope of
      remediation with respect to which the indemnified Party seeks
      indemnification, provided that the indemnifying Party shall not enter into
      any settlement that would materially affect the operations of the
      indemnified Party at the Yokkaichi Facility unless the indemnified Party
      has granted its prior written consent.

(b)   The Parties shall cooperate in good faith to seek to agree upon the means
      of joint defense of any third party claim giving rise to Covered
      Environmental Costs (with any disagreement to be resolved by the mediation
      and arbitration provisions set forth in Appendix A).

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5.5   Liability Limit. Neither Party's aggregate liability for Covered
      Environmental Costs or indemnification obligations under Sections 5.1, 5.2
      and 5.3 shall exceed the greater of US$5 million or the aggregate purchase
      price of Y3 NAND Flash Memory Products by such Party from the Company
      during the six years prior to the date of the applicable claim. (or in the
      case of liability arising after the FP Termination Date, for the six year
      period immediately preceding the FP Terminate Date).

6.    SATISFACTION OF INDEMNIFICATION OBLIGATIONS.

6.1   Prompt Payment. Each Party shall promptly pay its 50% share of any Covered
      Environmental Costs paid by the Company or by the other Party in excess of
      its obligation to bear 50% of the Covered Environmental Costs. In
      principle, Toshiba and SanDisk shall bear their respective 50% shares of
      any given Covered Environmental Costs via adjustments to the purchase
      prices they pay Company for Y3 NAND Flash Memory Products, pursuant to the
      applicable Master Operative Documents. The Parties shall discuss in good
      faith the means and the timing of payment of their respective 50% share of
      Covered Environmental Costs, taking into account when the Covered
      Environmental Costs are paid by the Company or by the other Party and the
      amount of such Covered Environmental Costs. To the extent the obligations
      of either Party will not be timely or fully retired by wafer price
      increases, the Parties shall directly pay their respective 50% share of
      Covered Environmental Costs.

6.2   Action in the Name of the Company. Either Party making a demand for
      indemnification or contribution pursuant to this Agreement shall be
      entitled, notwithstanding anything to the contrary in the Master Agreement
      or FP Operating Agreement, to cause the Company to make such demand, if
      doing so is appropriate to fulfill the intent of this Section 6 (e.g., if
      the Company has borne the Covered Environmental Costs and the claiming
      Party has already reimbursed the Company 50% of the same).

7.    POST TERMINATION ENVIRONMENTAL COSTS AND EXIT ENVIRONMENTAL REPORT.

7.1   Environmental Costs Paid Post Termination. Except as otherwise set forth
      in this Section 7, the Parties' obligations under Section 5.1 shall expire
      as of the FP Termination Date:

(a)   In respect of Environmental Costs for remediation, to the extent the Exit
      Environmental Report identifies contamination at the Y3 Facility and a
      good faith claim concerning shared responsibility for such remediation
      costs is made by one of the Parties before the FP Termination Date, any
      obligations of the Parties under Section 5.1(a) (subject to Section
      5.1(b)) in respect of remediation of such contamination shall survive the
      FP Termination Date, but only for so long and to the extent the Prudent
      Operator Standard continues to require remediation in respect of such
      contamination.

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(b)   In respect of Covered Environmental Costs resulting from a bona fide third
      party claim, the Parties obligations under Section 5.1(a) (subject to
      Section 5.1(b)) shall survive [***].

7.2   Exit Environmental Report.

(a)   Promptly upon (i) the exercise by either Party of any right under the FP
      Operating Agreement and/or Master Agreement to acquire the Units of the
      other Party in the Company, to sell its Unit in the Company to the other
      Party or to cause the dissolution of the Company, or (ii) entering into
      any letter of intent or agreement for the sale of the Y3 Facility or all
      or substantially all of the assets (leased or owned) of the Company, the
      Parties shall engage an environmental consultant from an internationally
      recognized environmental investigation firm that has experience in Japan
      and that is mutually acceptable to the Parties (the "Exit Consultant") to
      conduct and complete Phase I and Phase II investigations of the Y3
      Facility as of a date as close as practicable to but in any event in
      advance of the FP Termination Date. Toshiba shall facilitate the Exit
      Consultant's access to the Yokkaichi Facility as reasonably necessary to
      conduct such investigations.

(b)   The Exit Consultant shall be directed to prepare a draft report based on
      its Phase I and Phase II investigations and to deliver the draft report to
      SanDisk and Toshiba (and if either so directs, to any environmental
      consultant either Party has engaged for its own account). SanDisk and
      Toshiba, directly and/or through their respective consultants, shall have
      60 days from receipt to comment on the draft report (any such comment
      shall be delivered both to the Exit Consultant and the other Party and any
      consultant it engages for its own account). The Exit Consultant shall then
      be directed to issue to the Parties its final report (the "Exit
      Environmental Report"), which shall be final and binding on the Parties.

(c)   Covered Environmental Costs arising from the Exit Environmental Report
      process shall be payable as provided in Section 6.1.

(d)   Unless all payments due for Covered Environmental Costs in connection with
      the Exit Environmental Report process have been made before the FP
      Termination Date, the Buyer shall be entitled to withhold from the
      purchase price payable (or distributable) to Seller and place into third
      party escrow up to [***] of such purchase price (but not to exceed the
      balance of Seller's liability limit in Section 5.5), which shall serve as
      security for Seller's responsibility for Covered Environmental Costs
      determined pursuant to this Section 7.

7.3   [***]

8.    MISCELLANEOUS.

8.1   Survival. Sections 5, 6, 7 and 8 and Appendix A shall survive the
      termination or expiration of this Agreement.

[***] INDICATES THAT CERTAIN INFORMATION ON THIS PAGE HAS BEEN OMITTED AND FILED
SEPARATELY WITH THE COMMISSION PURSUANT TO RULE 24B-2. CONFIDENTIAL TREATMENT
HAS BEEN REQUESTED WITH RESPECT TO THE OMITTED PORTIONS.

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8.2   Entire Agreement. This Agreement, together with the exhibits, schedules,
      appendices and attachments thereto, constitutes the agreement of the
      Parties to this Agreement with respect to the subject matter hereof and
      supersedes all prior written and oral agreements and understandings with
      respect to such subject matter.

8.3   Governing Law. This Agreement shall be governed and construed as to all
      matters including validity, construction and performance by and under the
      substantive laws of Japan.

8.4   Dispute Concerning Prudent Operator Standard. Notwithstanding anything to
      the contrary in Section 2.5 of Appendix A, if the Parties are not able to
      agree upon what application of the Prudent Operator Standard requires with
      respect to any given proposed remediation hereunder, at the request of
      either of them they shall engage a neutral and independent environmental
      consultant acceptable to both Parties (the "Independent Consultant") to
      facilitate resolution of such dispute. The Parties (and at the option of
      each of them their own environmental consultants) shall meet and discuss
      the matter with the Independent Consultant and seek in good faith to
      resolve the dispute. If the Parties are not able to resolve the dispute
      within 60 days after initiating discussions with the Independent
      Consultant, then at any time after such 60 day period either Party may
      bring an arbitration claim pursuant to Section 2.5 of Appendix A to
      resolve the dispute concerning application of the Prudent Operator
      Standard.

8.5   Assignment. Neither party hereto may transfer this Agreement or any of its
      rights hereunder (except for any transfer to an Affiliate or in connection
      with a merger, consolidation or sale of all or substantially all the
      assets or the outstanding securities of such party, which transfer shall
      not require any consent of the other party) without the prior written
      consent of the other party hereto (which consent may be withheld in such
      other party's sole discretion), and any such purported transfer without
      such consent shall be void.

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      IN WITNESS WHEREOF, the Parties have caused this Agreement to be executed
and delivered as of the date and year first above written.

                                               TOSHIBA CORPORATION

                                               By:    /s/ Masashi Muromachi
                                                      --------------------------
                                               Name:  Masashi Muromachi
                                               Title: President and CEO
                                                      Semiconductor Company
                                                      Corporate Vice President

                                               SANDISK CORPORATION

                                               By:    /s/ Eli Harari
                                                      --------------------------
                                               Name:  Eli Harari
                                               Title: President and CEO

                                               SANDISK INTERNATIONAL LIMITED

                                               By:    /s/ Eli Harari
                                                      --------------------------
                                               Name:  Eli Harari
                                               Title: President

[Signature page to Mutual Contribution and Environmental Indemnification
Agreement]

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                                    EXHIBIT A

                                      [***]

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