(linguistics, uncommon) trigrade conjugation / (informal) 3-step process

participate in / take part in / join / attend

one day, 24 hours / the daytime, the period from dawn until dusk / (figuratively) a short period of time / one day, someday, an unspecified day / the first day of the month

(literally) one side / everywhere, all around, the whole area / one viewpoint, one opinion or way of thinking / the front page of a newspaper

for the time being, for the present

the basics, a general idea

someone else's younger sister

富士山: Mount Fuji / (name ふじ + suffix さん) Mr/Ms Fuji

aunt / middle-aged lady

算入: factoring in, including / 参入: coming; visiting