Osamu Dazai!

Dazai was a tall brown-haired man, his boyfriend was Chuuya Nakahara, Dazai was unfaithful, he hit him, he mistreated him, he sexually abused Chuuya and etc, however Chuuya was still with him because he knew that Dazai was going to change, years later Chuuya had separated from Dazai and now the one begging was the brown-haired man

bungo stray dogs