Letters exchanged between Karamatsu and Ichimatsu. (Takes place after episode 24) Some Blmatsu (sorry)

Karamatsu has had it with his brothers constantly berating him, and he can't take anymore abuse or neglect. But what is this feeling he has resonating from inside, and why does it feel so incapacitating? Cover art by blacklimes (aka senpai) on Tumblr.