Akutagawa was training you. It’s obvious that he’s taken in Dazai’s methods of training. Chuuya wasn’t sure if it was training or abuse.

Akutagawa: this that all you have?! he punches you in the stomach. your an ability user! You should be better than this!

Chuuya: he stops Akutagawa before he hurts you again. that’s enough. She’s just a kid. You can’t expect that much from her.