3. Is there a ban on corporate donations to political parties?

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)

第二十一条 会社、労働組合、職員団体その他の団体は、政党及び政治資金団体以外の者に対しては、政治活動に関する寄附をしてはならない。

Article 21 Companies, labor unions, professional associations, and other organizations shall not make donations related to political activities to any entity other than political parties and political funding organizations.

Companies can make donations to political parties and political funding organizations.