Aniki (兄貴, lit. "older brother") is a Japanese honorable term mainly used to refer to someone one considers a superior, within the context of the Yakuza franchise, though it may also be used for a literal older brother.
Quotations[]
Kazuma Kiryu — What are you getting at here? It's all 'aniki' this and 'aniki' that.
Rikiya Shimabukuro — It's 'cause you're my aniki. Duh.
Kazuma Kiryu — You're the captain of the Ryudo Family. I'm nothing to you, especially not your aniki.
Rikiya Shimabukuro — Eh, let's talk about this later.
Kazuma Kiryu — No. I can't have a yakuza talking to me like that. What would my kids think?
Rikiya Shimabukuro — C'mon, just let it slide! I respect your strength, that's all. Don't you see? You're my aniki, Aniki!
— Kazuma Kiryu and Rikiya Shimabukuro, Yakuza 3 Remastered
Yuta Usami — Huh!? What the hell? Cap? This guy is—
Tsuyoshi Nagumo — Shut yer trap! Y'oughta be showin' some respect! This guy's my aniki now! And you fools'll call him aniki too!
Yuta Usami — What!?
— Yuta Usami and Tsuyoshi Nagumo, Yakuza 6