In order to attend university in Tokyo, Go and his sister Noriho are staying at their older brother's house who lives alone in Tokyo. Riho is a stepchild of her father's remarried partner, and she is not related by blood. Riho has more feelings for Go than her brother, and if she has a chance, she will set up a sexy temptation, but Go will endure without crossing her line. However, Riho's huge breasts can't stop her brother from being horny.
