No Curse for the Inseparable Older Sister

Half a year after starting school, Ken lives with his older sister Chiyako because her place is closer to campus. She cooks for him, helps with studies, and becomes increasingly possessive. In the bathroom she finds him erect and begins oral sex. Later she handcuffs him and repeatedly forces intercourse while treating it as punishment. After getting a job she returns home and shows the handcuffs again, saying she will continue today.