て以来【ていらい】

て以来 means "ever since": after the event in the て-form, a new state set in and has lasted up to now. It follows the て-form of a verb, and the second half is a lasting state or a habit, often with ずっと, まいにち毎日 or いちど一度も〜ない.

It sounds formal and belongs to writing and careful speech. In conversation, てから does the same job: にっぽん日本にきて来てから、ずっとこのまち町にすんでいる住んでいる.

て以来 or てから

てから can also just mean "after": one action, then the next. て以来 cannot. The second half has to be something that has gone on since.

• × 朝ご飯を食べて以来、学校に行った → 朝ご飯を食べてから、学校に行った

Not for the recent past

て以来 looks back over a long stretch. For yesterday or this morning, it sounds out of proportion; use てから.

• × 昨日日本に着いて以来 → 昨日日本に着いてから

A noun can take 以来 directly, with no て-form: きょねん去年いらい以来, そつぎょう卒業いらい以来.