counter N1 uncommon writtenliterary

来 — for the past ~

来・らい

Meaning

for the past ~ / over the last ~ — a span of time continuing right up to the present

彼かれとは十年来じゅうねんらいの友人ゆうじんだ。

He and I have been friends for the past ten years.

Attaches to	Form	Example
Time-span noun	[time span] + 来らい	数年来すうねんらい

When: Written/formal; attaches to a span (十年じゅうねん, 数年すうねん, 長年ながねん) to mean 'continuing for that span up to now.'

数年来すうねんらいの懸案けんあんがようやく解決かいけつした。

A matter pending for several years was finally resolved.

長年来ながねんらいの夢ゆめがついに叶かなった。

A dream I'd held for many years finally came true.

The same 来らい appears in 本来ほんらい/従来じゅうらい/将来しょうらい, but those are fixed vocabulary, not this 'for the past ~' suffix.

Jengo shows 来 the way you actually meet it: inside real Japanese sentences, so it sticks instead of staying an abstract rule.

Sources Compiled with reference to A Dictionary of Intermediate Japanese Grammar.