UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

WASHINGTON, DC 20549

FORM 6-K

REPORT OF FOREIGN PRIVATE ISSUER

PURSUANT TO RULE 13a-16 OR 15d-16 UNDER

THE SECURITIES EXCHANGE ACT OF 1934

For the month of May 2025

Commission File Number: 001-42438

COINCHECK GROUP N.V.

(Translation of registrant’s name into English)

Nieuwezijds Voorburgwal 162

1012 SJ Amsterdam

The Netherlands

(Address of principal executive offices)

Indicate by check mark whether the registrant files or will file annual reports under cover of Form 20-F or Form 40-F:

Form 20-F ☒ Form 40-F ☐

On May 13, 2025, Coincheck Group N.V. (“Coincheck Group”) issued a press release, announcing its financial results for its fourth quarter and year ended March 31, 2025, which is furnished as Exhibit 99.1 to this Report on Form 6-K.

The information in this Report on Form 6-K is incorporated by reference into Coincheck Group’s Registration Statement on Form S-8 (File No. 333-286190), to the extent not superseded by documents or reports subsequently filed or furnished.

EXHIBIT INDEX

SIGNATURES

Pursuant to the requirements of the Securities Exchange Act of 1934, the registrant has duly caused this report to be signed on its behalf by the undersigned, thereunto duly authorized.

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