兄きょう弟だい分ぶん

noun

sworn brother; close buddy

Refers to a man who is like a brother through a pledge of loyalty, not by blood. Often used in yakuza or historical contexts, but can also describe a very close male friend.

• 彼かれは私わたしの兄きょう弟だい分ぶんで、何なんでも相そう談だんできる。