His mother died from illness when he was young, while his wealthy father was almost never home. Six months ago, his father brought Kumi into their lives. She resembles his late mother but is not related to him by blood and treats him like her own son. He initially resents her kindness, then realizes why: as an adult, he has begun to desire his stepmother as a woman. That attraction develops into a sexual relationship that consumes them both in this adult role-play.