expression, adverb
since that time; since then; from that point on
Used adverbially to mark a starting point in the past from which a situation has continued or changed.
彼はその時以来、一度も酒を飲んでいない。
He hasn't had a single drink since that time.
その時以来、彼女とは会っていない。
I haven't seen her since then.
Compound of その時 (that time) and 以来 (since, thereafter).