During the day - a first year high schooler bishoujo. After school - A little sister who only spoils me!?「Become a rental onii-chan so we can write a little sister type character」- that was the mysterious part time mission given by a game company.Furthermore the client said: 「If you become a little sister, Majima will give you lots of love, won't he?」At first she was only a bishoujo classmate but now all of a sudden she started acting sweet and our distance became closer!?