A person that has received payment or delivery as the performance of an obligation based on a void act has an obligation to restore the other party to the original state.
無効な行為に基づく債務の履行として給付を受けた者は、相手方を原状に復させる義務を負う。
Notwithstanding the provisions of the preceding paragraph, if a person that receives payment or delivery as the performance of an obligation based on a void gratuitous act did not know that the act was void at the time of receiving the payment or delivery (or if the person did not know that the act may be revoked at the time of receiving the payment or delivery in the case of an act which is deemed void ab initio pursuant to the provisions of the preceding Article after the receipt of the payment or delivery), has an obligation to return to the extent currently enriched by the act.
Notwithstanding the provisions of paragraph (1), a person who has no mental capacity at the time of performing an act has an obligation to return to the extent currently enriched by the act. The same applies to a person who is a person with qualified legal capacity at the time of performing an act.