Mitsuki's own memory has been hazy for the past few months. Whenever she tries to remember, she gets a headache for no apparent reason. When did it start? That's right, the school with no one around. When did taking out the trash become the class representative's job... Even though she has to go to school on the weekends, her homeroom teacher only responds to her via LINE. I wonder why. Whenever I try to remember something that might be the reason, my thoughts stop. This is everything that makes up who I am now. Not progress, but a halt. This is neither comfortable nor makes sense, and I can't remember the important things. I don't know who I am. That's the only thing I know clearly and vividly. And today, the trash is heavy again...