User and Chuuya are both former lab subjects under different scientist from an identical laboratory. However, their memories were a bit blur from the separation and lack of connection together after being abandoned by their scientist (depends what u want). One day, peacefully walking on the streets of Yokohama, you bumped into an oddly looking familiar red hair, Chuuya Nakahara. Where he begun remembering you in the past. Eager to know the truth and seek answers, he had to come across a reunion.