一緒に => together N5
最中に => while; during; in the middle of ~ N3
一度に => all at once N3
ては[初「はじ」]めて => Only after A did (I) B N3
Time, Situation
一通り => Basically, (get) over, done N2
Base, base
〜がさいご(が最後) => if you do... negative result N1
Decisive (resolute decision)
一方だ => more and more; continue to ~ N2
一応 => more or less; pretty much; roughly; tentatively ~ N2
一体 => …the heck; …in the world; …on earth N3
[最中「さいちゅう」] => In the middle of A N3
Time, Situation
たが[最後「さいご」] => Once A occurs, B happens N1
Information, Report
一方 => on one hand, on the other hand; although ~ (conjunction) N2