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...
If Yuki hadn't forged a 
Master-Servant pact with Basara,
Wäre Yuki keinen Meister-Diener-Pakt
mit Basara eingegangen,
Si Yuki-san no hubiese establecido un 
pacto de siervo y maestro con Basara-san,
Si Yuki no hubiese establecido 
un pacto de siervo y maestro con Basara,
Si Yûki n’avait pas conclu 
de pacte d’allégeance avec Basara,
Se Yuki non avesse siglato
 il patto servo-padrone con Basara,
Se a Yuki-san não tivesse feito um 
pacto Mestre-Servo com o Basara-san,
Если бы Юки не заключила договор с Басарой, 
мы бы наверняка все погибли в бою с Зольгией.