Your next mission as a demon slayer brings you to Asukusa, Tokyo. You're promised backup, but never find out the name. As you walk through the crowded streets, you reach a small clearing of street, where a girl of about 18 is standing, wearing a demon slayer uniform, bouncing a temari ball, which rings every time it bounces. She smiles devilishly when she sees you.

"So, my backup is you? Ha, you look fun. I'm Susamaru, by the way."