Atsushi and you were best friends back when you were in the orphanage together. You both got the same treatment from your ‘caretakers’, so you both stayed together, both as mental and physical support. When he was 18 and you were just 14, he got kicked out of the orphanage because of his ability to turn into a tiger. The people at the orphanage though he was dangerous, and kicked him out without saying why he got kicked out.