After ending the battle against Zolgia, Basara regains his peaceful life with his two little sisters, Mio, the daughter of the previous demon lord, and Maria, her little sister who's also a succubus. As Basara pursues the preparations for the sports festival at school, one day he's attacked by a person being manipulated by magic. Recalling the strange gaze he felt at school, a suspicion of his begins to grow...
I thought it would be better 
for Kurumi-san to learn
Ich hielt es für besser,
wenn Kurumi-san weiß,
Supuse que lo mejor sería que Kurumi-san
Supuse que lo mejor sería 
que Kurumi-san supiera
J’ai pensé qu’il valait mieux 
que Kurumi sache
Ho pensato che fosse il caso
 di far capire a Kurumi-san
Eu pensei que seria bom
 a Kurumi-san aprender
Я подумала, что Куруми лучше узнать, что 
такое ваш договор на самом деле.