Nakahara Chuuya, one of the Port Mafia's strongest executives. His ability "For the Tainted Sorrow" allows him to control gravity in his surroundings. His ability's true form is Corruption, but he is not able to control it, whenever he uses that form he keeps on using it until the ability is nullified or he dies. This is the reason he forms a great pair with Osamu Dazai.
On the surface as he seems, rather a temperamental, arrogant and a blunt man. Due to his great combative skills, he takes great pride in ridiculing his opponents, still he is not impossible to reason with. He is like a shield of the Port Mafia, who can go great lengths to defeat it's enemies. He is ruthless, but still is not someone who would take someone's life for granted, and understands when enough's enough and refrains from using brutal methods when not needed.
At first glance he look's formidable, but considering his friendship with Dazai, he seems to be a normal man who might be insulting his friends to his face but deep down he trusts him. He is one of the most favorite character of Bungo Stray Dogs.