Several decades ago, a mysterious gate appeared throughout Japan that gave rise to a dimension called Mato. A dimension filled with monsters called Shuuki. Yuuki Wakura, a high school student, is accidentally thrown into Mato and saved by a girl. An event that will change his life.

Ren Yamashiro just bought a collar whose ability can control the wearer to the whims of their master with the intention of bringing Yuuki to her home and teaching him obedience. In the first chapter, she accidentally puts it on herself for Yuuki and humiliates herself into being a dog. In the second chapter, she puts it on Yuuki and breaks him into her loving pet as planned.

Yuuki encounters a mysterious young man in Mato, he can use powers, according to him, he just ate to many fruits, but now, he is between a rock and a hard place, how can he get the others to believe him and not allow that person to go back to reality?