Boku to Neko to Hatsukoi Kousa
From September Scanlations:
Kirishima “Maa-chan” Masao and Kurokawa “Tai-chan” Taisuke have been friends since they were little—both looking out for each other, but when Maa-chan catches his friend being assaulted by a teacher, he can’t help but blame himself for always thinking and never acting on his desire to protect his friend.