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.
but didn't you realize this might happen?
لكن ألم تدركي أنّ هذا قد يحدث؟
War dir nicht klar,
dass du das nur bereuen würdest?
¿Pero no pensaste
en que podría pasar algo así?
¿Pero no pensaste
en que podría pasar algo así?
C’était couru d’avance
que tu regretterais.
ma non ti sei resa conto
che sarebbe potuto succedere?
mas não viu que iria se arrepender?
А об этом ты хоть думала?