留年の危機に瀕していた魔法学校の生徒・アルトは偶然見つけた本の魔法陣を発動させた結果、封印されていた悪魔・ヴェルメイを召喚してしまった! ヴェルメイは厄災ともいえる強大な力を持つ、大変不健全なお姉さんで!? 崖っぷち魔術師が最強の使い魔と歩む王道ファンタジー!!
Alto, an aspiring magician, is about to repeat a grade when he accidentally summons the demon Vermeil, which was sealed in a book Alto found by chance. Not only does Vermeil hold an ancient power capable of bringing about the end of the world, she’s also quite naughty! A traditional fantasy story about a struggling magician and his powerful familiar begins with their fateful meeting.
