Mizuto and Yume used to date, but now they've suddenly become stepsiblings. Both of them agree that they don't want to do anything that'd disappoint their newly remarried parents. However, neither of them can accept the other as being the eldest sibling in the relationship. So they both agree to settle the matter with a game. Whoever does something in conflict with what people might consider normal sibling behavior, loses. Making them the younger sibling.
I'm the only one in the entire school 
who knows you used to be a total nerd.
أنا الوحيد في هذه المدرسة بأكملها
.الّذي يعرف أنّك مولعة بالقراءة
Dass du eine kleine Streberin warst, …
Soy el único que sabe que solías ser
una maniática de cuidado.
Soy el único que sabe
que solías ser una friki de cuidado.
Je suis le seul à savoir qu’avant,
Sono l'unico in tutta la scuola
a conoscere il tuo passato da nerd.
Eu sou o único aqui que sabe que
você costumava ser uma nerd total.
Во всей школе только я знаю,
каким ботаншой ты раньше была.