It's the year 2269, and April Enus is working as a spy for the Alliance. She's known as "Venus" because of her special power: fatalities don't seem to happen when she's around. But is this power a blessing or a curse?

Her parent suddenly went to Brazil to work, in order to prepare for the entrance exam, Sakura went to live in her aunt's house. However, her aunt also went for a business trip, so now there was only Sakura in her aunt's house.

Then, the Uesakura sisters living in the neighborhood came to live with her. And a life with the older sister Ichiko, a high school girl who can't do any house work, the beautiful little sister Futako who is in the same school as Sakura and also the President of the Student Council, and her aunt's ten cats begins.