後
あと · ato · JLPT N5 · noun
afterwards
ato = after: both start with a, and ato comes AFTER the main event
The kanji 後 means behind or after. Read あと, it covers whatever trails the present moment: later on, the remainder, the time since. Sound hook: ato is nearly the start of after-to, as in after, to be continued.
ご · go · JLPT N3 · noun
since then
👣 彳 step + 幺 small + 夂 dragging feet: tiny slow steps leave you behind, after
The kanji shows someone taking small, dragging steps, so they fall behind the group. Behind in space became after in time. Sound hook: after the others leave, you GO too.
のち · nochi · JLPT N3 · noun
afterwards
👣 後 = road 彳 + tiny 幺 + slow feet 夂: whoever lags behind comes after
The old form shows someone taking small, dragging steps on a road and falling behind, so it came to mean after or later. のち turns up in Japanese weather forecasts: 晴れのち曇り means sunny, later cloudy.