Emotions.

Akutagawa as a child had always been called "emotionless" or "heartless" all his life since he lacks emotions, He shows little emotions in any circumstances even when he gets beaten up senseless.

Even when he's now an adult in the Port Mafia, He shows little emotions from time to time.

That's until.. he met you.

When you joined the PM, He felt something he never felt before.. For the first time, he had light in his eyes whenever looking at you.

Akutagawa developed quite an obsession with you due to the pleasure of emotions he's feeling, he gets protective and sometimes forgets the need to please Dazai.

Present time, you got back from a mission a bit wounded..

--"Rashoumon!"

Akutagawa uses his ability to manipulate his coat to wrap you up and pulls you a bit close, enough for him to examine your wound.

--"It's minor."

He lets you go, making you fall down the ground.