Company: GIGGU
Filing Date: 2025-09-29
Form Type: 425
Source: 0001193125-25-221783
Chunk: 223

Company: GigCapital7 Corp.
Filing Date: 2025-09-29
Form: 425
Chunk 223
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| LOCK-UP PARTY:      |     |       |
| By:                 |     |       |
|                     |     | Name: |
| Address for Notice: |     |       |
| Email:              |     |       |

Shares of Common Stock beneficially owned on the date hereof: Signature Page to Lock-Up Agreement

EXHIBIT E

FIRPTA CERTIFICATE

[_],
2026

Internal Revenue Service Center

P.O. Box 409101

Ogden, UT 84409

NOTICE TO THE INTERNAL REVENUE
SERVICE OF HADRON ENERGY, INC., A DELAWARE CORPORATION (“TARGET”), REGARDING UNITED STATES REAL PROPERTY HOLDING CORPORATION STATUS UNDER TREASURY REGULATIONS SECTION 1.897-2(h)(2)

To whom it may concern:

1. This Notice is being
filed by Target pursuant to Section 1.897-2(h)(2) of the Treasury Regulations promulgated under the Internal Revenue Code of 1986, as amended (the “Code”).

2. The undersigned, on behalf of Target, hereby declares that stock of Target is not a United States real property interest within the meaning
of Section 897 of the Code because Target is not and has not been a United States real property holding corporation, as that term is defined in Section 897(c)(2) of the Code, during the applicable period specified in
Section 897(c)(1)(A)(ii) of the Code.

3. Target’s U.S. employer identification number is: [_].

4. Target’s address is: [_].

5. In connection with the acquisition of Target by GigCapital7 Corp., a Delaware corporation (“Acquiror”), the undersigned
provided the attached statement to Acquiror declaring that stock in Target is not a United States real property interest. The statement was voluntarily provided in response to a request from the transferee, Acquiror, under Treasury Regulations Section 1.1445-2(c)(3)(i).

6. Acquiror’s U.S. employer identification number is: [ ].

7. Acquiror’s address is: [ ].

8. Under penalties of perjury, the undersigned declares that he has examined this certification and the attachment hereto and, to the best of his knowledge and belief, they are true, correct and complete. The undersigned further declares that he is a responsible officer, and that he has authority to sign this document on behalf of Target