He has a somewhat stocky build. In his first encounter, he wears a white T-shirt with a belly warmer, and a pair of slacks. When he acts as an assassin, he wears a windbreaker jacket and a pair of leather shoes, sometimes also wearing a black ski mask.
Hirose is a jovial senior and takes things in a laid-back fashion. He treats his subordinates like his own children.
Despite this, he's also a professional assassin and particularly skillful with knives and fights practically in battle. He is also a known schemer, ranging from scamming a hospital for insurance fraud after an accident and later manipulating Yuta to killing Big Lo claiming that he will come after Haruto when Kiryu goads him to facing his own fears. He is also an extremely capable infiltrator, being able to sneak into Little Asia, while carrying Haruto, and gets into Big Lo's office undetected. Big Lo himself said that the building was guarded by 100 men, all carrying firearms. This is also illustrated when he unknowingly joins in the family laughter (plus Kiryu) and no one noticed until they heard Hirose laugh too. Another skill that Hirose possesses is his immense presence as a yakuza and as an assassin, when he chooses to show it. When Big Lo threatens to sic all of the above-mentioned Saio Triad members on Hirose and kill him and Haruto as well, he merely looks at Lo with a bored look on his face, stating that he didn't care what they were carrying. He'd kill every single one of them, and this was enough to make Big Lo himself break out in a cold sweat, and agree to Hirose's terms.
Hirose lost both of his parents during World War II, and turned to crime in his youth as a result. He started his own gang at a very young age of 14 years old. Not long after the bombing of Hiroshima, Hirose's gang led an attack on a facility owned by Heizo Iwami's Iwami Shipbuilding company, and they were all caught. Iwami accepted Hirose into his organization and mentored him into becoming an assassin; in order to protect the secret of Onomichi, the most classified military secret in Japan that could cause a scandal bringing about an end to the career of Iwami's co-conspirator, military general Minoru Daidoji, Hirose became Iwami's most competent assassin and developed a bond of trust with him. Hirose accepted killing many men to protect the secret (some of whom were his aniki), despite Hirose accepting that he wouldn't know what he did, showing his trust to Heizo.
Two of the men Hirose killed were the fathers of Tsuyoshi Nagumo and Takaaki Matsunaga. As an act of compassion, Hirose adopted their sons as an act of compassion. In his later years, Hirose would become incorporated into the yakuza group that Iwami ran as a front for Iwami Shipbuilding; the Yomei Alliance. Despite Hirose's closeness to Iwami, his family, the Hirose Family, was made a subsidiary of the Masuzoe Family, with Nagumo being the Captain and Matsunaga being the lieutenant. Over the years, Yuta Usami, Naoto Tagashira and Shu Tatsukawa were sworn into the Hirose Family as well.
Yakuza 6: 2013-2016
Like the others in Onomichi, Hirose becomes friendly with Haruka Sawamura when she arrives in town. Months later, she rushes to him for help when she becomes pregnant with Yuta's child and his retainers try to pressure her into an abortion. Hirose helps her disappear by taking her to a small town not far from Onomichi. One day, with Haruto Sawamura in hand, Hirose confronts Big Lo in the latter's office and warns him to leave the country. Despite being outmanned by Lo's armed subordinates, Hirose is able to force him to accepting his terms with his presence. He also reveals that he is aware that both Koji Masuzoe and Tatsukawa are Saio Triad infiltrators, and demands he order them to stop their spying on him. He continues to watch over Haruka until she is lured to Kamurocho.
Hirose first meets Kiryu when Tsuyoshi Nagumo introduces them to each other. He is living off insurance fraud. Welcoming Kiryu jovially to the Hirose family, he builds a relationship with him to ensure his cooperation while staying in Onomichi, helping to take care of Haruto. Later, Hirose reveals that he knew all along that Yuta was the father of Haruto, and his involvement with Haruka's second disappearance. He kills Masuzoe for his insubordination. He then joins the other Hirose Family men and Kiryu on a boat to retrieve Haruto, where he secretly kills Joon-gi Han (who led the Jingweon Mafia hired as mercenaries by the Yomei) before he can reveal the secret of Onomichi to Kiryu.
Soon afterwards, Kiryu and the Hirose Family lead a raid on an Iwami Shipbuilding base. There, Hirose has a battle with Kiryu. In spite of his age, Hirose is able to put up a fight thanks to his skills with his knife, but is ultimately defeated. Afterwards, Tagashira causes the "secret of Onomichi", the Yamato Mark II, to reveal itself from the depths of the sea, with Hirose glad to be able to see it at last.
Hirose confesses to Matsunaga and Nagumo that he had killed their parents to protect his secret. At this point, Heizo Iwami appears, and demands that Hirose execute his children. When Hirose hesitates, Iwami shoots him and walks away. He confesses to his adoptive children that he wished they'd be the ones to kill him, and he passes away in front of them.
Despite his age, Chairman Kurusu claims that Hirose is the strongest person in Hiroshima. While not particularly proficient in hand-to-hand combat, he compensated it with excellent knife-wielding skills and marksmanship. His weapon of choice is a kitchen knife and a handgun. His knife attacks mainly consist of slashes and throws. Further into the fight, he also shows his knack for stealth by tossing a knife to a nearby steam pipe to create a makeshift smokescreen.