Hirose family was formed by Toru Hirose shortly after he adopted both Tsuyoshi Nagumo and Takaaki Matsunaga. Yuta Usami and Naoto Tagashira later joined them and formed the family. The family only consist of six people and working in protection racket. The members also joined a baseball team named Jingai Thunder and feared for their dirty reputation of injuring the opposing team.
At first, the Hirose Family are being hostile towards Kiryu during the beginning of the game for several reasons that caused their reputation to dwindle. But as the story progress, they've grown to become Kiryu's companions. Kiryu helped them several times in their own problems, and they also begin to support Kiryu in several instances. Nagumo and Yuta also accompany Kiryu during his trouble with the Jingweon Mafia and the Chinese Mafia in Kamurocho. When Haruto was kidnapped by Joon-gi Han, they do not hesitate to help Kiryu to save him, especially Yuta after his denial. But when Yuta accompany Kiryu to his third visit at Kamurocho, Yuta attempted to sacrifice himself with the Chinese Mafia in order to secure the future for Haruto and his partner, Haruka. Kiryu wastes no time to storm the burning Saio Triad headquarters and knock some sense into him and saved him. However, Big Lo, the head of Saio Triad, told Kiryu that Hirose was actually the killer who kill anyone who knows about the secret of Onomichi.
Their trust to Kiryu begins to falter when he revealed that Hirose was the serial killer who protected the Onomichi Secret. However, they quickly get into the same page to uncover the secret of Onomichi. After Hirose is revealed to be the killer and was shot by Takeru Kurusu, he revealed to Nagumo and Matsunaga that he was the one who killed their fathers for knowing the secret of Onomichi and apologizes before dies from his injuries. After Hirose's death, Nagumo takes over as the patriarch of the Hirose Family. Kiryu then gives them word of encouragement and their friendship with Kiryu grows even stronger than before. Together, they defended Hirose's house against the attacking members of Yomei Alliance.
The Hirose Family accompanies Kiryu to Kamurocho for the fourth time. With the help of Shun Akiyama, they stormed the Millenium Tower in order to confront Sugai. However, Sugai was not in the building, and instead, Someya was there. After Someya stabs himself and Kiyomi was seemingly shot by Koshimizu, Someya entrusted Nagumo to take care of his and Kiyomi's daughter.
During the final battle, Nagumo and Kiryu confronts Sugai, Tsuneo, and Koshimizu in Takeru Kurusu's funeral. Together, the duo defeated Koshimizu. Unfortunately, the Yomei Alliance has captured both Haruka and Haruto and hold her hostage, leaving Kiryu no choice but to take beatings. Thankfully, Yuta, Naoto, and Matsunaga come to his aid and save Haruka, allowing Kiryu to fight Iwami and defeats him. Although Kiryu was shot by Sugai in order to protect Haruka and her family, Naoto disarms Sugai and the entire Hirose family surrounds him. Sugai then decided to commit suicide after admitting defeat. They're all visibly sad when Kiryu said his last words to Haruka before succumbing to his wounds.
In the epilogue, Nagumo has a talk with Someya's daughter and reveals that Kiyomi is actually still alive. Yuta now lives with his family in Okinawa as the new owner of Sunshine Orphanage. It is unknown about what happened to the rest of the family, but it can be assumed they resumed their normal life in Onomichi.
Toru Hirose is the patriarch of the Hirose Family. According to Nagumo, he is said to have taken the front line during the Yomei Alliance war with the Omi Alliance. During his younger times, he was a gang member of street punks. He was recruited by Takeru Kurusu for his bravery. He is later entrusted to protect the secret of Onomichi and kill everybody who knows about it. He killed both Nagumo and Matsunaga's father and adopted them. During the present, he threatens Big Lo to keep his mouth shut about the Onomichi Secret and killed both Masuzoe and Joon-gi Han for the sake of it. After his true identity was revealed by Kiryu and the secret of Onomichi was revealed, Hirose hesitates to follow Takeru's order to kill all of his underlings who apparently have grown to cared for them. After Hirose was shot down by Takeru, he thanked Kiryu for allowing him to see what the secret truly is and admits to Matsunaga and Nagumo about their father's murder and apologizes before dying.
Tsuyoshi Nagumo is the Captain of the Hirose Family. He starts rivalry with Kiryu due to jealously of seeing him with Kiyomi, the woman whom he had crush with. After Kiryu saved him from the Masuzoe family and witnessed his wisdom, Nagumo comes to respect Kiryu and calls him 'brother'. Nagumo and Yuuta accompany Kiryu in Kamurocho against the Chinese Mafia, and also helped him to rescue Haruto from the Jingweon Mafia. He begins to distrusts Kiryu after he told them that Hirose is a serial killer but reconcile shortly during their attempt to reveal the secret of Onomichi. After Hirose's death, Nagumo took over as the patriarch of Hirose Family and his friendship with Kiryu grows stronger. He accompanies Kiryu during his fourth visit to Kamurocho during the raid at Millenium Tower, and during their final battle against Sugai and Iwami.
He once saved Haruka Sawamura from a paparazzi and develops feelings for her until he unknowingly impregnates her. He accompanies Kiryu during his errand at Kamurocho with Nagumo. When it was revealed that Haruto is his son, Yuta went into shock and denial but was able to put himself together thanks to Kiryu. However, he planned to kill himself with the Saio Triad in order to protect his loved ones. Thankfully, Kiryu arrived just in time to beat the sense into him and saved him. He stays with Haruka in the hospital and joins up with Kiryu, Akiyama, and the others to the Millenium Tower. Yuta was injured in the process but later able to save Haruka from the Yomei Alliance, allowing Kiryu to defeat Iwami. After Kiryu was shot to protect him and his family, Kiryu entrusted Haruka and Haruto's future in Yuta's hands. In the epilogue, he became the owner of Morning Glory Orphanage in Okinawa and lived happily with his partner and son.
Matsunaga was adopted by Hirose alongside Nagumo after their father was murdered by him. Despite his stern appearance, Matsunaga goes through life with an easygoing disposition. At first, he's being hostile with Kiryu for messing with the family's rep, but come to respect him after he was revealed to be the Dragon of Dojima. He helped Kiryu several times alongside his friends including rescuing Haruto. He also distrusts Kiryu after what he said about Hirose being the killer but reconcile during their attempts to discover the Onomichi secret. After Hirose's death, his friendship with Kiryu grows stronger after his words of encouragement and helped him during the raid at Millenium Tower. He alongside Yuta and Naoto arrived to rescue Haruka during the final battle, allowing Kiryu to defeat Iwami.
Naoto was recognized by his chubby features. He appears to be hostile to Kiryu when they first time met but come to respect him. He helped Kiryu to rescue Haruto and also the one who's responsible for revealing the secret of Onomichi. He later accompanies Kiryu during the raid at Millenium Tower and rescue Haruka during the final battle. He also manage to disarm Sugai and corners him.