Grey Lie (Soukoku)

While trying to hide the fact that he was in the Port Mafia from Dazai, Chuuya Nakahara finally finds out that Dazai Osamu was a part of the organization he tried to protect the brunette from. In the face of the truth, Chuuya wasn't sure if he should feel the same way towards his so called lover anymore.
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Chuuya grew up in a mafia organization, Inogashira, raised by his non biological father. With no one who actually cared for him or even acknowledged his existence as Chuuya and not Chuuya Inogashira, his only light in life was the note from her that fluttered down from the same tree every night. All was well until the whole organization fell apart, massacred, along with her.
Losing his only hope in life, Chuuya follows the head of Port Mafia as a student and also new member. His suspicion that the Port Mafia was the one behind the slaughter of Inogashira and her death arises as he delves deeper into the organization.