One question why are they all students?

because like 80% of manga/anime has teenage protagonists.

something to do with Japanese Life basically sucking after you graduate high school so they preserve the last vestiges of their happy pure lives via entertainment media (manga, anime, etc)

let me rephrase: I shouldn't say Japanese Life but rather adulthood in general. i realized after replying that my comment may have came across rather rude.

i meant that life after high school, that is "Adulthood", just kind of sucks for most people. so the manga/anime/etc entertainment media focuses on the period of time before adulthood, that is teenage years.

i honestly came blame them, being an adult sucks. i don't want to read about crappy adult life but rather fun fantasy kid life so i can escape my boring adulthood for a little while.