<PAGE>

                                  Exhibit 10.4

                      Real Estate Buying/Selling Agreement

This Agreement is made by and between the Wonderful Internet Technology
(hereinafter referred to as the "Buyer") and Chiu, Yu-En (hereinafter referred
to as the "Seller") for the selling of the premises (as described below), on
terms and conditions mutually agreed as follows:

1.    Total Buying /Selling Amounts

      Total amounts shall be FORTY-EIGHT MILLION New Taiwan Dollars.

2.    Deadline of Payments and Premises Transfer

i.   At the time of execution of this Agreement, the Buyer shall pay to the
     Seller partial of the total amounts of (intentionally blank) New Taiwan
     Dollars (including deposit).

3.   According to the above-mentioned (intentionally blank), the Seller agrees
     to supply Title of Ownership; and in accordance with (intentionally blank),
     the Seller shall supply all premises related documents, such as Seal
     Certification, Household Information, and Title Transfer Registration
     Application which are sealed by the registered agent. Afterwards, if
     coordination, supplement of seal and/or certification replenishment/change
     are needed, the Seller agrees to supply immediately without any delay,
     refusal or reparations. The Buyer agrees to supply all title transfer
     related documents to the scrivener for signing/transferring a deed within
     five days. If the Seller's rights are damaged as result in discovery of
     delay by the Buyer, the Buyer shall be responsible for all losses of the
     Seller.

4.   Taxes and Registration Expenses

i.   The Seller accepts full and sole responsibility for the payment of all
     taxes attached to the premises, such as: land value tax, house tax,
     expenses paid for the benefit derived from public construction projects
     (including those are not levied yet), land rental, electricity, water, gas,
     telephone and building management/security bills till on the date the Buyer
     moves into the premises. The Buyer shall pay all taxes and bills in the
     following day.

ii.  The increment tax on land value is to be paid by the Seller whilst the
     Buyer agrees to pay the deed tax.

iii  The Buyers agrees to pay scrivener, registration, notarization expenses (or
     supervision expenses) and stamp duty, etc. (The Buyer shall deduct the
     amounts of the above-mentioned taxes and expenses which shall be paid by
     the Seller).

5.   In the event of the processing of the title transfer and registration, the
     Buyer shall have full right to assign and transfer this Agreement without
     further consent from the Seller. The Buyer shall be responsible for joint
     responsibilities of warranties and waiving the right of prosecution
     rebuttal appeal. In terms of the processing of the title transfer and
     registration, the Buyer shall apply within seven days upon receipt of all
     documents provided by the Seller. Any of tax raising and other damages
     caused by this overdue application, the Buyer shall pay for it except for
     those stipulated payment responsibilities during the period of this
     Agreement. The Buyer and the Seller shall be responsible for taxes paid
     within three days upon the tax rates of the increment tax on land value and
     deed tax approved by the government. No delay is allowed. If any loss
     caused by either party's negligence, the one shall be responsible for it.

6.   Under the circumstance of the total amounts paid with bills which have been
     returned and provided by the Seller, the Buyer shall bear for all
     responsibilities of the terms of not paying on schedule as well as the
     terms of those outstanding bills within seven days, and the Seller is
     entitled to claim from the Buyer for those bills resulting therefrom. Under
     no condition

<PAGE>

     shall the Buyer bear the violation.

7.   The Seller warrants that he has lawful title to the premises. If the
     warranty is breached by others or erections of other rights, the Seller
     shall be responsible for defining the title by odd sum paid. Any damage
     might occur to the Buyer with result in above, the Seller bears
     responsibility for any reparation occurs.

8.   In order to processing loans smoothly and to ensuring two parties'
     benefits, under no conditions, the Buyer shall provide all necessary
     documents and sufficient collateral to warranty loans. The loans are
     insufficient as requested as a result the occurrence of the Buyer's credit
     are not qualified or the changes of financial strategy, the Buyer shall
     replenish in cash once and the total loans shall be paid within three weeks
     upon completion of the title transfer processing. Both also agree to
     deliver the premises to the Buyer upon the date of odd sum paid. With
     concurrence of the Seller, the Buyer shall borrow keys to meet
     repair/maintenance requirements, and the Buyer shall pay the down payment
     in accordance with the terms and conditions stipulated on the Agreement and
     shall warranty not moving-in. Under no condition, if the warranty is
     breached, all repairs and alterations shall be confiscated by the Seller

9.   In terms of those fixed facilities such as in- and out-house doors,
     windows, kitchens, toilets and public facilities as well as additional
     portion before move-in, the Seller shall not withdraw or damage arbitrarily
     and shall also recover those auxiliary water, electrical and sanitary
     facilities currently existed and shall transfer to the Buyer with the
     original shape and in normal use. Whenever the premises or any essential
     part thereof shall be intruded or destroyed by typhoon, fire, earthquake,
     war, civil disturbance, or any other casualty, the Seller shall be
     responsible for repelling or repair in order to allow the Buyer to obtain
     it completely.

10.  Upon the occurrence of the Buyer's denial to buy the premises or amounts
     are not being paid according to the Agreement, and ignoring the Seller's
     timely notice of payment, under no conditions, the Seller has the right to
     confiscate all amounts which have been paid by the Buyer as penalty and
     terminate this Agreement.

     Upon the occurrence of the Seller's denial to sale the premises or failure
     to implement the duties in accordance with the Agreement, all receivable
     amounts have to be returned to the Buyer with additional indemnity, same
     amount as received from the Buyer. Under this circumstance, under no
     conditions, this Agreement will be terminated.

11.  The Seller shall be responsible for delivery the premises on the date, the
     same time when the Buyer paid the odd sum of the total amount, stipulated
     on the Agreement, without any procrastination or delay receiving the odd
     sum and delivery the premises. Upon the occurrence of postponement, the
     Seller shall pay penalty, at the rate of one-thousands of the total amount
     since the date of delivery the premises, to the Buyer.

12.  This Agreement shall be governed by and construed in accordance with the
     laws of the Republic of China. The parties hereto expressly submit any
     disputes or controversies to the local courts of Taiwan of first instance,
     unless otherwise stated. This Agreement is executed in two identical sets
     of copies, each of which is deemed to be an original, one set to be held by
     the Buyer, and the other set to be held by the Seller.

13.  The parties shared evenly the handling charges of signing this Agreement in
     amount of (intentionally blank) New Taiwan Dollars and paid off when this
     Agreement is being signed. All terms and conditions stipulated on this
     Agreement shall ensure the parties' own willingness and shall be recognized
     by both parties without any mistakes. Upon the occurrence of dispute or not
     being corresponded with the actual situation, the scrivener shall be
     irrelevant to it.

14.  Specified terms and conditions:

<PAGE>

Real Estate Indication:
Land located at:        8(th) Floor and 8th -1 Floor, 98, Mingchuan Road,
                        Hsintein City, Taipei
                        Land No./Scope:  Partial

Premises located at:    8(th) Floor and 8th -1 Floor, 98, Mingchuan Road,
                        Hsintein City, Taipei
                        Premises No./Scope:  All and partial of its public
                        facilities

The Buyer:              Wonderful Internet Technology (sealed)
                        WANG, KUO-AN (Sealed)
                        Business Uniform No. 70676630
                        Tel. No.
                        Address:

The Seller:             Chiu, Yu-En (Sealed)  The above-mentioned
                        ID No. A121216698       business shall be closed
                        Tel. No.                after the odd sum of the
                        Address:                total amount is being
                                                paid by the Buyer and
Date April 2000                                 loans are being obtained
                                                by the Seller on the date
                                                of (intentionally blank).
                                                and, the title of the
                                                premises is being
                                                transferred to and
                                                obtained by the Buyer.
                                              The Buyer:  (intentionally blank)
                                              The Seller: (intentionally blank)

The Bank of Panhsin Application for Remittance

                          To be filled by the Applicant

                                5 October, 2001

<TABLE>
=================================================================================================================
<S>                  <C>                                        <C>
  Forwarding
     Bank              Bank Taipei, Chungho Branch                            Remittee Name
-----------------------------------------------------------------------------------------------------------------
   Remittee
  Account No.          0 7 6 5 0 1 9 1 4 6 6 0 0                                Chiu, Yu-En
-----------------------------------------------------------------------------------------------------------------
   Amount:                                                                          Amt
  NT Dollar          NINE MILLION SEVEN HUNDRED FIFTY           -------------------------------------------------
(Black Letter)        THOUSAND New Taiwan Dollars               + C
---------------------------------------------------------       [X]T+   [X][ ][ ]                 $ 9 7 5 0 0 0 0
                Remitter                                        -------------------------------------------------
---------------------------------------------------------                       Hdling Fee
Name [ ]                       Tel. No.[ ] 22185996             -------------------------------------------------
                                                                [X]C+
Kid Castle Internet Technology Corporation                      T+   [X][ ][ ]                            $ 1 1 0
                                                                -------------------------------------------------
ID/Business Uniform No.[ ]                                      Total
                                                                -------------------------------------------------
70676630 Remarks: Repaid loan and cancellation                  Acct No.              0 4 4 6 1 4 1 0 0 0 0 6 6 0
                                                                -------------------------------------------------
Address [ ]                                                     Bill No.
                                                                -------------------------------------------------

1st Floor, No. 148, Chienkuo Road, Hsintien City, Taipei        Seal: The Bank of Panhsin, Hsintien Branch, 5 Oct
                                                                2001, Transfer Seal (3) (Sealed)
-----------------------------------------------------------------------------------------------------------------
</TABLE>

                                  Verification

<TABLE>
<CAPTION>
-----------------------------------------------------------------------------------------------------------------
                              Machine  Cashier  Remit.               Forwarding  Remittee Account
Date      Time      Seq..No.    No.     No.     Type     Remit. No.    Bank No.         No.
-----------------------------------------------------------------------------------------------------------------
<S>       <C>       <C>       <C>      <C>      <C>      <C>         <C>         <C>
5-Oct.-   14:51:41  0000313      A3    0446003  General  0000278      0510291       00765019146600
2001
-----------------------------------------------------------------------------------------------------------------
                                                                                   ID/Business
Remittance Amount             Remit. Fee        Handling Fee         Remitter      Uniform No.
-----------------------------------------------------------------------------------------------------------------
$9,750,000.00  TR             $60.00  CS        $50.00  CS           Kid Castle        70676630
                                                                     Internet
                                                                     Technology Corp.
-----------------------------------------------------------------------------------------------------------------
   Remittee Name                                                     Remarks
-----------------------------------------------------------------------------------------------------------------
   Chiu, Yu-En                                                       Repaid loan and cancellation
-----------------------------------------------------------------------------------------------------------------
                                                 Reason for
                                                 Remittance
     Item                  Supv(1)  Supv(2)      Returning                               Closed (sealed)
-----------------------------------------------------------------------------------------------------------------
</TABLE>

<PAGE>

The Bank of Panhsin Application for Remittance

                         To be filled by the Applicant

                                5 October, 2001

<TABLE>
=================================================================================================================
<S>                   <C>                                       <C>
  Forwarding
     Bank              Bank Taipei, Chungho Branch                            Remittee Name
-----------------------------------------------------------------------------------------------------------------
   Remittee            0 7 6 5 0 1 9 1 4 6 6 0 0
 Account No.                                                                  Chiu, Yu-En
-----------------------------------------------------------------------------------------------------------------
   Amount:                                                                      Amt
  NT Dollar           TWENTY MILLION New Taiwan Dollars         -------------------------------------------------
(Black Letter)                                                  + C
---------------------------------------------------------       [X]T+   [X][ ][ ]               $ 2 0 0 0 0 0 0 0
                 Remitter                                       -------------------------------------------------
---------------------------------------------------------                       Hdling Fee
                                                                -------------------------------------------------
 Name [ ]                       Tel. No.[ ] 22185996            [X]C+
                                                                T+   [X][ ][ ]                            $ 2 1 0
Kid Castle Internet Technology Corporation                      -------------------------------------------------
                                                                Total
ID/Business Uniform No. [ ]                                     -------------------------------------------------
                                                                Acct No.              0 4 4 6 1 4 1 0 0 0 0 6 6 0
70676630 Remarks: Repaid loan and cancellation                  -------------------------------------------------
                                                                Bill No.
Address [ ]                                                     -------------------------------------------------

1st Floor, No. 148 Chienkuo Road, Hsintien City, Taipei         Seal: The Bank of Panhsin, Hsintien Branch, 5 Oct
                                                                2001, Transfer Seal (3) (Sealed)
-----------------------------------------------------------------------------------------------------------------
</TABLE>

                                   Verification

<TABLE>
<CAPTION>
-----------------------------------------------------------------------------------------------------------------
                              Machine  Cashier  Remit.               Forwarding  Remittee Account
Date      Time      Seq..No.    No.     No.     Type     Remit. No.    Bank No.         No.
-----------------------------------------------------------------------------------------------------------------
<S>       <C>       <C>       <C>      <C>      <C>      <C>         <C>         <C>
5-Oct.-   14:50:36  0000312     A3     0446003  General   0000277      051291      00765019146600
200
-----------------------------------------------------------------------------------------------------------------
                                                                                      ID/Business
Remittance Amount             Remit. Fee        Handling Fee         Remitter         Uniform No.
-----------------------------------------------------------------------------------------------------------------
$20,000,000.00  TR           $100.00  CS        $100.00  CS          Kid Castle        70676630
                                                                     Internet
                                                                     Technology Corp.
-----------------------------------------------------------------------------------------------------------------
   Remittee Name                                                     Remarks
-----------------------------------------------------------------------------------------------------------------
   Chiu, Yu-En                                                       Repaid loan and cancellation
-----------------------------------------------------------------------------------------------------------------
                                                 Reason for
                                                 Remittance
     Item                  Supv(1)  Supv(2)      Returning                               Closed (sealed)
-----------------------------------------------------------------------------------------------------------------
</TABLE>

<PAGE>

                         Mortgage Cancellation Agreement

Ref. No.:  Bank Taipei-Chungho-Tze No.1

Due to debt repaid, Chiu, De-Tsai agrees to cancel all mortgage registration at
     the maximum amount of TWENTY-FIVE MILLION New Taiwan Dollars in accordance
     with the Receiving Document No. 86-Hsin-Den-Tze No. 220250 on June 16, 1997
     issued by the Office of Land Administration, Hsintien City, Taipei.

BTAIPEI

Agreed by:           Bank Taipei
   Person-in-charge: Ho, Show-Chung
   Address: No. 36, Nanking East Road, Section 3, Taipei

    Agent:           Bank Taipei, Chungho Branch (Office)
   Manager (Supervisor): Pan, Quen-Chyung (sealed)
   Address: No. 55, ChungchEn Road, Yungho City, Taipei

Date:                8 October 2001

Form No. A87018790

<PAGE>

                         Mortgage Cancellation Agreement

Ref. No.:  Bank Taipei-Chungho-Tze No.2

Due to debt repaid, Chiu, De-Tsai agrees to cancel all mortgage registration at
     the maximum amount of SEVENTEEN MILLION AND FIVE HUNDRED THOUSAND New
     Taiwan Dollars in accordance with the Receiving Document No.
     86-Hsin-Den-Tze No. 220260 on June 16, 1997 issued by the Office of Land
     Administration, Hsintien City, Taipei.

BTAIPEI

Agreed by:           Bank Taipei
   Person-in-charge: Ho, Show-Chung
   Address: No. 36, Nanking East Road, Section 3, Taipei

Agent:               Bank Taipei, Chungho Branch (Office)
      Manager (Supervisor): Pan, Quen-Chyung (sealed)
      Address: No. 55, ChungchEn Road, Yungho City, Taipei

Date:                8 October 2001

Form No. A87018791