Tatsuuma Ushiyama (牛山 辰馬, Ushiyama Tatsuuma), also known as Ushiyama the Undefeated (不敗の牛山, Fuhai no Ushiyama), is one of the Abashiri Convicts and a crucial member of Hijikata's Group. He is a master judoka, being considered the strongest and most dangerous fighter out there.
Ushiyama is a hulking Japanese man with a thick mustache, a cauliflower ears and hair slicked on the back of the head. He has a square bump on his forefront because of his thick skull. Ushiyama is incredibly muscled because of his daily training. His torso and back are covered in Noppera-Bou's map.
Ushiyama usually wears a two pieces suit to blend in.
Ushiyama is a pragmatic and serious criminal. Aiming to steal the Ainu gold, Ushiyama is focused on his mission and always threads with prudence, regularly offering reasonable advice to Hijikata.
He is also a womanizer. Ushiyama lusts after any beautiful woman he comes across and is very direct when he solicits sex. It is his main way of distracting himself. He claims that in a relationship, a man's penis is the most important factor, but says that it has to be "gentlemanly".
As a judoka, Ushiyama relishes fights and challenges. When he met Sugimoto, he was impressed favorably by his strength and befriended him. He likes to fight and had a great time clashing with Sugimoto, being disappointed when it was interrupted. Ushiyama is confident in his fighting prowess to the point he will challenge a (weakened) bear in combat and even briefly taunts it about spreading his legend among bears when he forces it to flee.
- Expert Judoka: In order to increase the power of his sweeps, Ushiyama practices kicking a 60kg bag of rice every day. In fact, his sweeps are good enough that most opponents often find themselves flipped head over heels before they even register what's going on.
- Great Physical Strength: Ushiyama possesses a level of might which few can match, being able to easily lift and throw a full-grown adult across a room and through ceilings.
- Great Physical Toughness: Beside his near superhuman strength, Ushiyama is more then capable of coming out unscathed from almost any kind of damage, with his skull in particular being so incredibly thick that not even a slash from Hijikata's katana could pierce it.
- Ushiyama likes peaches and beer but has no dislikes.
- He was modeled after Tatsukuma Ushijima, a Japanese judoka and former All-Japan judo champion. His nickname was "The Demon Ushijima".
- Ushiyama is taller than Ariko and Tanigaki, making him the tallest character in the series.
- Ushiyama is heavier than Tanigaki and Sofia, making him the heaviest character in the series.
- In 2018 Golden Kamuy All-Stars popularity poll, Ushiyama ranked 17th, gaining 2,406 votes. 
- According to Golden Kamuy anime character reference sheet, Ushiyama's height is 188 cm (6'2). 
- In the VIZ Media English translation and fan-translations, Ushiyama's name is translated as Tatsuma instead of Tatsuuma.
|Warden||Shirosuke Inudou †|
|Staff||Toshiyuki Kadokura ☓ • Tokishige Usami ☓|
|Convicts||Anji Toni † • Fusatarou Oosawa † • Heita Matsuda † • Kanjirou Kasahara † • Kano Ienaga † • Kazuo Henmi † • Keiichirou Sakamoto † • Keiji Ueji † • Kiichirou Wakayama † • Kiyohiro Suzukawa † • Maiharu Gansoku • Michael Ostrog † • Mutsuo Tsuyama † • Noppera-Bou † • Shiton Anehata † • Soroku Funabashi † • Takechiyo Gotou † • Tatsuma Ushiyama • Tetsuo Takarai † • Tetsuzou Nihei † • Toshizou Hijikata • Waichirou Sekiya † • Yoshitake Shiraishi • Youichirou †|
|Main Group||Kantarou Okuyama • Kirawus • Rikimatsu Ariko • Shinpachi Nagakura • Tatsuma Ushiyama • Toshiyuki Kadokura • Toshizou Hijikata|
|Former Members||Anji Toni † • Hyakunosuke Ogata • Kamezou † • Kano Ienaga †|
|Associates||Kenzou Tamoto • Kiroranke † • Takuboku Ishikawa • Yoshitake Shiraishi|
|Main Group||Asirpa • Saichi Sugimoto • Yoshitake Shiraishi|
|Former Members||Cikapasi • Fusatarou Oosawa † • Genjirou Tanigaki • Inkarmat • Kiroranke † • Retar • Ryu • Vasily|
|Associates||Hajime Tsukishima ☓ • Hyakunosuke Ogata ☓ • Otonoshin Koito ☓ • Tatsuma Ushiyama|