最中に => while; during; in the middle of ~ N3
〜がさいご(が最後) => if you do... negative result N1
Decisive (resolute decision)
に行く/に来る/に帰る => go/arrive/go back (to do something) N5
[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
へ => Go to N, head to N , Often followed by verbs like 行く/いく, 来る/くる, 向かう/むかう… N5
Particles