My Wife's Secret My Wife Doesn't Know What I Know... Mako Oda(2017)

Husband Kazuhiro’s older brother Masayuki loses his job and everything, and ends up staying with the couple for a while. Wife Mako reluctantly agrees to her husband’s suggestion. The recently divorced Masayuki, despite knowing she is his brother’s wife, cannot suppress his arousal simply from living under the same roof with a woman. Mako struggles with the illicit relationship with her brother-in-law and lives in constant fear that Kazuhiro will find out, yet he continues treating her exactly as usual, whether he knows or not…