ตอนที่ 1: บาสาระพบกับน้องสาวปีศาจคนใหม่และเปิดเผยต้นกำเนิดฮีโร่เพื่อปกป้องพวกเธอ

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While Basara Toujou and his father Jin await the former's new little sisters from the latter's remarriage, Basara inadvertently encounters Mio Naruse in a restroom. Eventually, Mio and Maria Naruse is introduced to Barasa as his new pair of little sisters. The following day, Maria leaves an incest-themed video game in Basara's sleep as Maria crawls into his bed as an act of "service." After saving Mio from a group of thugs, Basara brings her to a spot overlooking the city where Mio states her appreciation to Basara as her new older brother. Momentarily after Jin's abrupt overseas leave, Maria and Mio orders Basara to leave his house whilst introducing themselves as demons; Mio is the heir in the title of Demon Lord; however, Basara reveals himself as a member of the hero clan and drives Maria and Mio away from his house. Basara soon receives word from Jin that Maria is in danger from the current demon lord's ploy to take Maria's inherited strength from his late-father, Wilbert. Meanwhile, Maria and Mio fight off evil forces until Maria is thrown off. Basara saves Maria from falling to her death and states he came back for his family as he shows their family photograph. (Source: Wikipedia)