Good faith must exist at the time of the entry into possession.
Civil Code
2015 English source edition · Current applicability not established.
This is the 2015 English-language edition attributed in its front matter to the Ministry of Justice. Eri Atlas has not independently verified the translation, later changes, or whether the text is currently in force. Nine passages are incomplete in the available scan and are identified where they occur.
Article 988
Time When Good Faith Must Exist · Preserved transcription; page attribution imported from the source collection. Verify against the original.
Discovery by the possessor that he acquired the thing from a person who was not entitled to transfer the ownership thereof shall be of no effect where such discovery occurs after the thing comes into his hands.