去る
さる · saru · JLPT N3 · verb-godan
to leave
🐒 saru also means monkey (猿): the monkey leaves
去る and 猿 (monkey) are both read saru, so the homophone is the hook: saru = monkey = the one who goes away. The kanji 去 is the same one in 過去 (kako, the past) — time that has left.
去 — 土 earth on top + 厶 (originally 凵, a vessel/container) below
Originally a pictograph showing a person (大) departing from an enclosed area or vessel, suggesting leaving or going away. Over time the top simplified to 土 and the bottom to 厶. The core meaning 'to go, to leave, to depart' has remained stable since ancient Chinese.