Ya all I've seen the raws he really did mistook the older brother as the younger one since they've met along time ago where he was helped by a younger brother then later on he saw the older brother in Uni and approached him first thinking that it was him (that young particular kid) since it was long ago also and he can't really remember the face since they almost look the same.
Additionally him going nuts was influenced by someone
damn
I was in highschool when I started reading this and now I'm preparing to be an engineer soon, what I really don't like about this story is the update but can't do anything about it I love the small changes in their relationship Sou is slowly accepting Mori hoping to see more progress soon
Marufok si antehhhh