Honjou Kaede is invited by her friend Shiramine Risa to play a virtual reality MMO game with her. While Kaede doesn't dislike games, what she really, truly dislikes is being in pain. She creates a character named Maple, and decides to put all her points in VIT to minimize pain. As a result, she moves slowly, can't use magic, and even a rabbit can get the best of her. But as it turns out, she acquires a skill known as "Absolute Defense" as a result of her pumping points into VIT, as well as a "Counter Skill" that works against special moves. Now, with her ability to nullify all damage, she goes on adventures.

Surrounded by a forest and a gated entrance, the Grace Field House is inhabited by orphans happily living together as one big family, looked after by their "Mama," Isabella. Although they are required to take tests daily, the children are free to spend their time as they see fit, usually playing outside, as long as they do not venture too far from the orphanage — a rule they are expected to follow no matter what. However, all good times must come to an end, as every few months, a child is adopted and sent to live with their new family... never to be heard from again. However, the three oldest siblings have their suspicions about what is actually happening at the orphanage, and they are about to discover the cruel fate that awaits the children living at Grace Field, including the twisted nature of their beloved Mama.

Morphed into a raccoon beastman, Michiru seeks refuge, and answers, with the aid of wolf beastman Shirou inside the special zone of Anima-City.