Clipping of エレキテル (erekiteru). / Clipping of エレキギター (ereki gitā, “electric guitar”).

solar calendar

lunisolar calendar / lunar calendar / Tenpō calendar

for a while, for a period of time

a while, a period of time

importance

historic, historical / already-happened, past / former, old, traditional

historian

study of history

(Internet slang, especially anime and manga fandom) events or things from the past which one wants to whitewash/erase from history (due to it being embarrassing, poorly received, etc.); dark past