I went to Tokyo for an exam and ended up staying at my brother's place temporarily. One night, I accidentally saw my brother and his wife having a secret moment. His wife had her face buried in his crotch while on all fours with her ass sticking out. I was overcome by a moment of madness, and it seems my brother's wife found out about me jerking off while watching that scene… 'My younger brother-in-law is getting excited because of me...' Understanding it this way, my sister-in-law has been pouring her lust into me since the next day...
