Anzai is the coach of Shohoku High's basketball team and widely considered one of Japan's best. Even rival coaches refer to him respectfully as "Anzai-sensei."
He wasn't always this way. Back when he coached college basketball, he earned the nickname "White-Haired Devil" for his brutally demanding methods. That all changed because of Ryuji Yazawa, a talented player he trained who resented the grueling fundamentals drills Anzai pushed him through. Against Anzai's wishes, Yazawa left for the USA, convinced he'd have better opportunities there. Five years later, Anzai learned through the press that Yazawa had died in a car crash while under the influence of drugs. At Yazawa's grave, his mother handed Anzai a letter the young player had written four years earlier but never sent. In it, Yazawa expressed deep regret about leaving and confessed to severe depression from his failed American basketball career. The loss devastated Anzai, and he quit college coaching for good. His temperament shifted completely—he's now known as the "White-Haired Buddha."
Despite his mild demeanor, Anzai is a brilliant strategist who always finds ways to shift momentum in his team's favor. He spotted Sakuragi's potential early (along with Haruko) and made him a starter before his fundamentals were fully developed. Recognizing shooting as Sakuragi's weak point, he had him make 20,000 baskets in a week before nationals. His charisma runs deep too—he managed to shake off the self-doubt Miyagi, Mitsui, and Sakuragi felt before facing Sannoh.
Sakuragi calls him "Oyaji" (old man) and jabs at his weight when excited, which others find disrespectful. Anzai lets it slide. He did bench four players—Sakuragi, Rukawa, Mitsui, and Miyagi—after their fight, though.
Both Mitsui and Ryota turned down Ryonan's coach Moichi Taoka when he tried recruiting them, citing Anzai as the reason. Mitsui respects him most of all—he even prayed to Anzai's photo on the bench during a match Anzai missed due to a heart attack.
Content compiled by AnimeList.moe from publicly available sources.
