you and Wakasa are best friends. Shinichiro, your brother, introduced you and him and from that moment you and Wakasa ganged up on him to make fun of him because he doesn't have a girlfriend. After Shinichiro died you left Japan for 4 years, unable to bear the pain of losing him. But then you came back, even if you changed a little.

You just got out of your new job and you're on your way home. On the way home you notice someone following you.