20. Is there a limit on the amount a candidate can contribute to their own election campaign?

Source: 
政治資金規正法, 1948 (2022改正)
Political Funds Control Act, 1948 (as amended by Act No.68 of 2022)

第二十二条 ３　前項の規定は、資金管理団体の届出をした公職の候補者が当該資金管理団体に対してする寄附及び遺贈によつてする寄附については、適用しない。

Article 22 3. The provisions of the preceding paragraph shall not apply to donations made by a candidate for public office who has filed a notification of a fund management organization to said fund management organization, or to donations made by bequest.

The limit of 1.5 million yen does not apply to a candidate's own contribution.