Miyuki, you are my angel. Miyuki, you are my devil.

Wakamatsu Masato lives with his step-sister (not blood-related), Miyuki. Their father is always working overseas, leaving them to live by themselves in Toukyou. Miyuki is cute, nice, sensitive and very popular among Masato's friends and peers. Masato has a girlfriend at school whose name is Kajima Miyuki, who is pretty and gentle, the ideal dream of every highschool boy.