How do you say sex in Japanese?
— 性別 (seibetsu); 性別

Specialized synonyms for sex in Japanese
homosexuality同性愛
love恋人 (こいびと, koibito)
pleasure喜び (よろこび) (yorokobi)
Generic synonyms for sex in Japanese
family親戚 (しんせき, shinseki), 親類 (しんるい, shinrui), 親族 (しんぞく, shinzoku)
Attributes for sex in Japanese
female雌 (めす, mesu)