Form SCHEDULE 13D BlockchAIn Digital Infra Filed by: Tiger Cloud LLC

The business address of each of the Reporting Persons is c/o BlockchAIn Digital Infrastructure, Inc.,1540 Broadway, Ste 1010, New York, NY 10036.

The principal business of Tiger Cloud is to provide management services, including operations management, strategic leadership, research and development, human resources, administrative workflow management, and other related management activities. The principal business of VCV Digital is to act as a venture capital company specializing in technology, digital assets, blockchain, and AI. Mr. Tang is the managing member of Tiger Cloud and VCV Digital and the Chief Executive Officer and Chairman of the board of directors of the Issuer.

During the last five years, none of the Reporting Persons has been convicted in a criminal proceeding (excluding traffic violations or similar misdemeanors).

During the last five years, none of the Reporting Persons has been a party to a civil proceeding of a judicial or administrative body of competent jurisdiction and as a result of such proceeding were or are subject to a judgment, decree or final order enjoining future violations of, or prohibiting or mandating activities subject to, federal or state securities laws or finding of any violation with respect to such laws.

Tiger Cloud LLC is a Delaware limited liability company. VCV Digital Solutions LLC is a Delaware limited liability company. Jerry Tang is a citizen of the United States.

The information set forth in Item 4 hereof is hereby incorporated by reference into this Item 3, as applicable.

On March 16, 2026, in connection with the consummation of the transactions (the "Business Combination") contemplated by the Business Combination Agreement, dated as of May 27, 2025, (as amended, the "Business Combination Agreement"), by and among BlockchAIn Digital Infrastructure, Inc. (the "Issuer"), Signing Day Sports, Inc., BCDI Merger Sub I Inc., BCDI Merger Sub II LLC, and One Blockchain LLC ("One Blockchain"), the Issuer completed the Business Combination and filed an amended and restated certificate of incorporation. Pursuant to the Business Combination Agreement, BCDI Merger Sub II LLC, a wholly-owned subsidiary of the Issuer, merged with and into One Blockchain, with One Blockchain surviving as a wholly-owned subsidiary of the Issuer (the "One Blockchain Merger"). The securityholders of One Blockchain received shares of Common Stock as part of the Business Combination. In connection with the One Blockchain Merger, the membership interests of One Blockchain outstanding prior to the Business Combination were automatically cancelled in exchange for the right of the holders thereof to receive the number of the Issuer's common shares as described in the Business Combination Agreement. Immediately prior to the One Blockchain Merger, Tiger Cloud was the owner of approximately 33.7% of the One Blockchain membership interests and VCV Digital was the owner of approximately 45.4% of the One Blockchain membership interests. As a result, following the Business Combination, Tiger Cloud received 15,100,970 shares of Common Stock and VCV Digital received 11,196,244 shares of Common Stock. The Reporting Persons continuously assess the Issuer's business, financial condition, results of operations and prospects, general economic conditions, other developments and additional investment opportunities. Depending on such assessments, and subject to any restrictions described herein, the Reporting Persons may acquire additional securities of the Issuer or new securities of the Issuer or may determine to purchase, sell or otherwise dispose of all or some of the Issuer's securities beneficially owned by the Reporting Persons in the open market, as applicable, in privately negotiated transactions, in transactions directly with the Issuer or otherwise. Such actions will depend upon a variety of factors, including, without limitation, current and anticipated future trading prices, the financial condition, results of operations and prospects of the Issuer, alternative investment opportunities, general economic, financial market and industry conditions and other factors that the Reporting Persons may deem material to their investment decision.

As of March 16, 2026, Tiger Cloud directly owned 15,100,970 shares of Common Stock and VCV Digital directly owned 11,196,244 shares of Common Stock. Mr. Tang, as managing member of Tiger Cloud and VCV Digital, may be deemed to beneficially own the shares owned by Tiger Cloud and VCV Digital. The shares owned by Tiger Cloud represent approximately 40.1% of the 37,629,068 shares of Common Stock outstanding upon consummation of the Business Combination. The shares owned by VCV Digital represent approximately 29.8% of the 37,629,068 shares of Common Stock outstanding upon consummation of the Business Combination. Mr. Tang, as the managing member of Tiger Cloud and VCV Digital, may be deemed to beneficially own an aggregate of 26,297,214 shares of Common Stock, representing approximately 69.9% of the 37,629,068 shares of Common Stock outstanding upon consummation of the Business Combination.

As of March 16, 2026, Tiger Cloud directly owned 15,100,970 shares of Common Stock and VCV Digital directly owned 11,196,244 shares of Common Stock. Mr. Tang, as managing member of Tiger Cloud and VCV Digital, has sole voting and dispositive power over the shares held by each of Tiger Cloud and VCV Digital and may be deemed to beneficially own the shares owned by Tiger Cloud and VCV Digital.

Information with respect to all transactions in the shares of Common Stock beneficially owned by the Reporting Persons that were effected during the past sixty days is set forth in Item 4 and 6 is incorporated herein by reference.

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The responses to Items 3, 4 and 5 are incorporated by reference into Item 6. Joint Filing Agreement Pursuant to Rule 13d-1(k) promulgated under the Exchange Act, the Reporting Persons have entered into a Joint Filing Agreement, a copy of which is filed hereto as Exhibit 99.1, with respect to the joint filing of this Schedule 13D and any amendment or amendments thereto. Business Combination Agreement On March 16, 2026, the Issuer consummated the Business Combination contemplated by the Business Combination Agreement, dated as of May 27, 2025, (as amended and as may be amended, supplemented or otherwise modified from time to time, the "Business Combination Agreement"), by and among BlockchAIn Digital Infrastructure, Inc. (the "Issuer"), Signing Day Sports, Inc., BCDI Merger Sub I Inc., BCDI Merger Sub II LLC, and One Blockchain LLC ("One BlockChain"). Pursuant to the Business Combination Agreement, the securityholders of One Blockchain received shares of the Issuer's Common Stock as part of the Business Combination. The description of the Business Combination Agreement is qualified in its entirety by reference to the full text of such agreement, a copy of which is filed as Exhibit 99.2 hereto. Lock-Up/Leak-Out Agreements In connection with the consummation of the Business Combination, certain stockholders of Signing Day Sports and certain equity holders of One Blockchain (collectively, the "Lock-Up Parties") entered into Lock-Up/Leakout Agreements (the "Lock-Up Agreements") with the Issuer. Pursuant to the Lock-Up agreements, subject to certain exceptions, the Lock-Up Parties, owning approximately 70.1% of the Issuer's common shares after the Closing, agreed not to sell, transfer, pledge or otherwise dispose the Issuer's common shares received in connection with the Business Combination for a period of 6 months following the Closing Date. Despite the transfer restrictions, a holder may transfer up to 25% of their restricted securities without restriction if, after the Closing Date, the Issuer's common shares on NYSE American trade at or above $9.375 per share (subject to adjustment for stock splits and similar events) for at least 20 out of any 30 consecutive trading days. The description of the Lock-Up Agreement is qualified in its entirety by reference to the full text of such agreement, a form of which is filed as Exhibit 99.3 hereto.

Exhibit 99.1 Joint Filing Agreement, as required by Rule 13d-1(k)(1) under the Securities Exchange Act of 1934, as amended. Exhibit 99.2 Business Combination Agreement, dated May 27, 2025, by and among Signing Day Sports, Inc., One Blockchain LLC, BlockchAIn Digital Infrastructure, Inc., BCDI Merger Sub I Inc., and BCDI Merger Sub II LLC* (incorporated by reference to Annex A-1 to the Registration Statement on Form S-4 (File No. 333-291856) filed on January 30, 2026). Exhibit 99.3 Lock-up/Leakout Agreement dated March 16, 2026 (incorporated by reference to Exhibit 10.1 to the Current Report on Form 8-K filed on March 18, 2026).