Summer break has arrived for the students with the highest exam scores, but it looks like Kyousuke will be stuck in school... However,
when Eiri is suddenly summoned home, Kyousuke discovers her family has asked for him, too! He worries his stay with House Akabane, a family of assassins, will be a dangerous one, and Eiri isn't enthusiastic to return home. Surprisingly, they're met with a warm reception! ...So then why does Eiri look so sullen? The sweet, summery fourth volume heats up in the romantic comedy where the more Kyousuke loves, the more dangerous his life becomes!