Kobato and Osanai made a pact to lead a quiet life as regular students upon entering high school. However, soon after, a handbag mysteriously disappears at the school, and Kobato is asked to help solve the case.
We'd promised that was 
what we'd do for each other.
.قطعنا وعدًا أنّ ذلك هو ما قد نفعله لبعضنا
Ci siamo scambiati questa promessa.
Prometemos que era isso
que faríamos um pelo outro.
Мы же обещали,
что будем помогать друг другу.