"Thank god that it was me for the first time." This demon... she's a mob and a non-capture character, but she's good at sex!! If she stays like this, she will enter the devil brothers' hard sex route and die again. Therefore, Mia uses the heroine's enormous magical power to raise her youngest child, Mob Devil Caius, as her bodyguard! However, the way she transfers her magical power is...extraordinarily pleasant sex!?At every place...in various positions...a demon piston that won't stop no matter how many times you go! Kaius, aiming to overthrow her older brothers, devours Mia's body with bottomless energy. The love flags that pop up one after another and the appearance of the older brothers. What is the fate of Mia, who longs for peace...!?