Itsuki Hashima is a popular, young novelist. However, he is obsessed with little sisters and his works seem to always include little sisters, so there’s some difficulty coming up with a new series. One day, his younger step-brother Chihiro and his colleagues, Hayato Fuwa, Nayuta Kani, and fellow college student, Miyako Shirakawa show up at his apartment. They enjoy dinner, drinks, and a game. That night, Nayuta makes advances towards Itsuki, but...
You can call me Onee-chan at any time.
Puedes llamarme hermana cuando quieras.
Puedes llamarme hermana cuando quieras.
Tu peux m’appeler grande sœur,
tu sais.
Lascia stare le formalità, chiamami pure sorellona!
Pode me chamar de 
Onee-chan se quiser.
Не стесняйся, зови меня сестрёнкой.