「おいで オレが守ってあげる」小説家・友一のピンチを救ったのは“吸血鬼”ケイト。突然「恋人」宣言して友一の血を要求＆押しかけ同居！ なんだコイツ（怒） オレ様で口も悪いケイト――だけど、素直に独占欲をぶつけてくるピュアさに、友一は今までに感じたことない程ドキドキ動転しちゃって…!? Ｓで一途な吸血鬼との恋!!
Sagara Yuichi is an aspiring writer who was caught in a convenience store robbery. Despite having the chance to escape, he lingered to gain writers experience, and ended up getting stabbed. During his last breath, a strange guy appeared claiming it was fate. A few hours later he awakens and finds himself sleeping naked next to that strange guy. Then that strange guy tells him that his blood is "S-Class" and that he's going to be Yuichi's lifetime "partner". Will the pragmatic novelist be able to wrap his mind around all this...?!