Considered the strongest Captain in the Gotei 13, Yamamoto is portrayed as an elderly man with a long beard. His torso and head bear numerous scars, hinting at countless battles in his past. He wears the standard Shinigami Captain uniform, but it's exaggeratedly oversized. Instead of wearing his haori properly, he drapes it over his back. Despite his advanced age, he has a remarkably muscular physique. As the general of the Gotei 13, Yamamoto commands immense respect from many Shinigami, particularly Komamura Sajin, who regards Yamamoto as a savior who saved his life. Known for his fiery temper, like Captains Byakuya Kuchiki and Soi Fon, he believes in strict adherence to laws for the community's benefit and despises rule-breakers.
Yamamoto founded the Shinigami Academy approximately 2000 years before the main Bleach storyline. He was a teacher there and personally trained Kyouraku and Ukitake. He admits to being quite proud of them, boasting about them as if they were his own sons when they became Captains. It has been revealed that he ordered Urahara Kisuke to stabilize the Garganta gate so that Captains could pass through, and he has dispatched four Captains to support Ichigo's team.
Yamamoto's Zanpakutou is Ryuujin Jakka (Flowing Blade like Flame). It is the oldest and most powerful fire-based Zanpakutou, surpassing all others in attack power within Soul Society. In its sealed form, it disguises itself as Yamamoto's staff, which transforms into a sword on command. The Shikai command is "reduce the whole of creation to smoldering ashes." Upon release, Ryuujin Jakka engulfs Yamamoto and his surroundings in flames. The sheer power of these flames can disintegrate almost anything the sword is swung at. Only formidable fighters like Kyouraku and Ukitake can withstand it. Even in its Shikai state, Ryuujin Jakka's power is sufficient to battle two other Captains' Shikai simultaneously.
His prowess as a Shinigami is evident; he brought 8th Division Lieutenant Nanao Ise to her knees and immobilized her merely by releasing his spiritual pressure. He also fought on par with two of the most powerful Captains, Shunsui Kyouraku and Jūshirō Ukitake, for a considerable duration without showing any signs of injury, while they sustained minor wounds.
