Tamotsu Hidoro led the Hidoro Family, a criminal syndicate operating in the river port town of Barato. He displayed distinctive facial tattoos and an eccentric personality, often carrying himself with a confidence verging on arrogance. He shared leadership of the family with his wife, widely regarded as the true mastermind behind their operations.

Married with a son named Shinpei Hidoro, Tamotsu remained unaware of his own sterility. Shinpei was not his biological child but the product of his wife's affair, a secret kept until a pivotal confrontation. The family ran a gambling hall, which became the epicenter of violent conflict when Tamotsu announced his intention to bequeath it to Shinpei. This succession plan provoked his right-hand man, Umakichi Kusuda, who felt betrayed. Kusuda split the gang, waging war against the Hidoro family for control of Barato.

Amidst this gang war, Tamotsu's wife disclosed the truth about Shinpei's paternity. Enraged by her infidelity and Shinpei's status, Tamotsu killed his wife, exposing the volatile and destructive nature of their relationship. The conflict escalated further when the Hidoro family acquired a tattooed convict's skin, attracting larger factions hunting for Ainu gold. Toshizou Hijikata and Shinpachi Nagakura offered their services as bodyguards to the Hidoros, ostensibly to end the war against Kusuda's faction. Conversely, Hyakunosuke Ogata allied with Umakichi Kusuda, intensifying the power struggle.

Tamotsu Hidoro met his end during the Battle in Barato arc, concluding his direct involvement in the narrative. Within the broader series context, he was a minor character, ranking 156th with 36 votes in a 2018 popularity poll.