悪友[akuyuu] undesirable friend
畏友[iyuu] one's esteemed friend
益友[ekiyuu] good friend
学友[gakuyuu] school friend
級友[kyuuyuu] classmate

旧友[kyuuyuu] crony
血友病[ketsuyuubyou] haemophilia
交友[kouyuu] friend
交友関係[kouyuukankei] one's relationships
校友[kouyuu] schoolmate

異類[irui] varieties
一類[ichirui] same kind
円虫類[enchuurui] round worms
塩類[enrui] salts
塩類溶液[enruiyoueki] saline

貝類[kairui] shellfish
柑橘類[kankitsurui] citrus fruits
希土類[kidorui] rare earth
魚貝類[gyokairui] marine products
魚類[gyorui] fish