When Yuko randomly runs into her aloof classmate Arisa one day, she's delighted to get a chance to get to know her! She cheerfully accompanies her to Shibuya, where Arisa says she has an important job that only she can do. As the situation turns violent, Yuko realizes that the mysterious Arisa has a lot more secrets than she could have guessed. Is Arisa involved with the urban legend of the "Execution Girl," who punishes evildoers?

Onizaki Teppei is a high-school freshman who just wants to live a plain student life, but his world is rudely shaken by a mysterious girl, Mitogawa Enma, who declares her intent to find a husband at the school!