Amai Akuma Ga Warau

Amai Akuma Ga Warau summary:

Haruru Shirosaki, a girl whose father is a director, is always busy. Her best friend is Mami. She visits a girl's school across the road from a boy's school. One day she sees a boy in the window of the boy's school. When she comes home from school the boy she had seen earlier is there saying he will become her butler? Is this just a dream?