When I got a job and started living alone in the countryside, I returned to my parents' house for the first time in six years and found that my sister Rin's breasts, which used to be small, had become huge. Rin saw her father masturbating and found out that her mother was not having sex with her. She felt sorry for her and wanted to do something that felt good for her mother, so she asked him if he wanted to touch her breasts if he wanted.