Exhibit 5.1

[David M. Bovi, P.A. Letterhead]

October 23, 2026

Onfolio Holdings Inc.

1007 North Orange Street, 4th Floor

Wilmington, Delaware 19801

Via E-Mail Only

Re: Registration Statement on Form S-1

Gentlemen:

We have acted as counsel to Onfolio Holdings Inc., a Delaware corporation (the “Company”), in connection with the Registration Statement on Form S-1 filed by the Company (the “Registration Statement”) with the Securities and Exchange Commission (the “Commission”) under the Securities Act of 1933, as amended (the “Securities Act”). The Registration Statement relates to (i) $55,000,000 of shares of Common Stock (the “Facility Shares”); and (ii) 1,000 shares of Common Stock issued as a commitment fee pursuant to the Facility (the “Commitment Shares”, collectively with the Facility Shares, the “Shares”), pursuant to an equity purchase facility agreement, dated as of April 10, 2026, between the Company and the selling stockholder named in the Registration Statement (the “Facility Agreement”). Capitalized terms used in this letter and not otherwise defined shall have the meanings given to such terms in the Registration Statement.

The opinions expressed herein are limited exclusively to the Delaware General Corporation Law, and we have not considered, and express no opinion on, any other laws or the laws of any other jurisdiction.

In rendering the opinions expressed herein, we have examined and relied upon the originals, or copies certified to our satisfaction, of:

In making the foregoing examinations, we have assumed the genuineness of all signatures, the authenticity of all documents submitted to us as originals, the conformity to original documents of all documents submitted to us as certified or photostatic copies thereof and the authenticity of the originals of such latter documents. As to all questions of fact material to this opinion, where such facts have not been independently established, we have relied, to the extent we have deemed reasonably appropriate, upon representations or certificates of officers of the Company or governmental officials and representations of the Company. Further, with your permission, we have made and relied upon the following assumption, without any investigation or inquiry by us, and our opinions expressed below are subject to, and limited and qualified by the effect of, such assumption that a sufficient number of shares of the Company’s Common Stock will be available and reserved for issuance of the Facility Shares. We have not verified any of these assumptions.

Based upon and subject to the foregoing, we are of the opinion that the Shares have been duly authorized and the Commitment Shares are, and when issued and sold by the Company and paid for in accordance with the terms of the Facility Agreement, the Facility Shares will be, validly issued, fully paid and non-assessable shares of Common Stock.

We hereby consent to the filing of this opinion with the Commission as Exhibit 5.1 to the Registration Statement, and to the reference to our firm under the caption “Legal Matters” in the Registration Statement. In giving such consent, we do not hereby admit that we are in the category of persons whose consent is required under Section 7 of the Securities Act. This opinion is rendered to you as of the date hereof and we assume no obligation to advise you or any other person hereafter with regard to any change after the date hereof in the circumstances or the law that may bear on the matters set forth herein even though the change may affect the legal analysis or legal conclusion or other matters in this opinion.

Very truly yours,