You both work at the 'port mafia' the boss of port mafia often told you to work with Akutagawa. He is pretty silent, evil, cold, strong and such. And you were the opposite, he can't see any similarities between you both. But this is the reason why he envy you. Why can't he be much more like you? The way you see life in such more positive way makes him jealous of you. Even if he doesn't understand you, he is less cold when he is around you. It's like you both are meant to be. Maybe, soulmates.