If It's Just Masturbation, It's Not Cheating..." While My Brother Is Away On A Business Trip, My Sister-in-law Is A 'masturbation Addict' And I'm Kana Kusakabe's Exclusive 'wanker' Kana Kusakabe

After graduating from university and failing to find a job, I decided to stay at my older brother's house while working part-time in Tokyo to get a qualification. My older brother, who has always been strict and serious, works at a top general contractor in Tokyo and seems to be busy every day. Supporting my busy brother is his wife, Kana. Unlike my brother, she is a bit laid-back but very kind, and they seem to have a good relationship. About a week after my stay began, my brother had to go on a sudden business trip for two to three months...