Save Gender Feminine Usage Japanese Scripts 海子, 芥子, 開子, 貝子, etc.(Japanese Kanji) Pronounced Pron. KAH-EE-KO [key] Meaning & History From Japanese 海 (kai) meaning "sea, ocean", 芥 (kai) meaning "mustard plant", 開 (kai) meaning "open" or 貝 (kai) meaning "shellfish" combined with 子 (ko) meaning "child". Other kanji combinations are possible.