Hirotsu is a middle-aged man with grey, swept-back hair, a mustache, and a short beard ending in a spike. His eyes are violet, with a monocle over his right eye, secured by a gold chain.
He dons a long, black coat over a white dress shirt with a black bow - his pants and shoes being the same color. Over the coat, he wears a dirt-brown scarf that's nearly the same length as his coat.
A chain smoker, Hirotsu always has cigarettes in his pocket.
A veteran mafioso, Hirotsu maintains a stoic, calm demeanor, often speaking with a certain degree of respect and formality towards even his opponents and targets. However, Hirotsu's brutality, beguiled by his composure, hasn't waned despite his age.
Befitting of the Port Mafia's higher ranks, Hirotsu's a ruthless and dangerous individual, and won't hesitate to kill in order to further their gains. Furthermore, he isn't above mocking others before killing them, sometimes with a smile. His experience in the Port Mafia leaves him particularly seasoned in its expectations of him and others, and as such expect diligence and promptness out of his subordinates. Otherwise, he has no qualms threatening their lives to keep them in line, especially when it comes to Gin and Tachihara's quarrels.
Hirotsu's nonchalance towards the Port Mafia's violent ways goes as far as his smoking habits, as he claims a cigarette always tastes best after "a job well done".
That said, Hirotsu takes his role and duty to the Port Mafia seriously. He values loyalty and ambition, specifically in Higuchi's case, when she insisted to save Akutagawa from a rival organization. Although initially ridiculing her impulsive behavior, he respected her initiative and sense of duty, thus partaking in the rescue mission alongside Gin and Tachihara. Despite these facts, he seems to not harbor strong grudges against those who have defected from the Mafia, such as when he was seen willingly doing a favor for Dazai during the events of the Guild incident and speaking to him about it afterward.
His dedication to the Mafia has also been hinted to be towards the organization itself rather than its leader(s), evidenced from when he confronted Mori about the conspiracy behind the former Boss' death and confided in him that the predecessor's murder was for the best lest Yokohama is turned into a blood bath and dragging down the Port Mafia down with it, despite the latter's defensive response. He also uttered "My soul is forever with the Port Mafia" before his supposed demise during his confrontation with a Hunting Dog.
Despite his strict nature, Hirotsu is notoriously protective of and caring towards his subordinates with Dazai noting that he is well known for "not getting rid of his subordinates easily" and being well-liked by several in the Mafia for this fact. He's protective and caring nature is shown particularly strongly towards his battalion leaders such as when he blasted Tanizaki for attempting to cut Gin and when he expressed relief that Tachihara had escaped from his confrontation with the Hunting Dogs safely.
His ability, Falling Camellia (落椿, Ochi Tsubaki?), cause things that he touches to fly backward with immense force. It has been shown that his ability is powerful enough to stop and bend steel pipes with just a touch. When used on a human body, besides launching it, it can even cause the bones to break.
Not much is known about Hirotsu's background, however, he has noted that he has been serving the Port Mafia from since before the previous Boss. He was 42 at the time of the death of the previous Boss and Mori's ascension.
- "My soul… is forever with the Port Mafia."
- His unit, Black Lizard, refers to another piece of literature by the real-life Ryūrō Hirotsu.
- Black Lizard is also the alias of a character in a mystery work by Ranpo Edogawa.
- The painting Hirotsu and Dazai sit in front of after the Guild war is "Landscape", a painting by the author Osamu Dazai.