In Japanese, what does the word "kimashita" mean and how does it work?

Question

In my text book it says “kimashita” is the past form of “to come”.

But then in the textbook it says:

How long have you worked here?
Koko de wa dorekurai hataraite kimashita ka?

How does “kimashita” mean “come” in this context?

In this question/answer it says that -ていく (te iku) and -てくる (te kuru) mean a change in state. That would explain the use of te in hataraite, but I am not sure how the information in that question/answer relates to the use of kimashita in the example phrase (in the textbook kimashita is described as meaning the past form of to come. What does came having to do with working?)

Answer 1

In Japanese, there is something called a subsidiary verb. Read this first: What is a subsidiary verb?

A subsidiary verb is similar to English have to as in "I have to swim" and be going to as in "I'm going to swim". See how these have and go have lost their original meanings.

来る (kuru) on its own means "to come", but as a subsidiary verb (i.e., after the te-form of another verb), it means something different. As a subsidiary verb, くる (kuru) is usually written with hiragana, and it typically describes:

• an action/state which has been kept/continued/repeated until now
• a gradual state change over time up until now
• a physical movement toward the speaker

くる in 働いてくる (hataraite kuru) is used in the first sense above. In this case, you can translate it either simply as "have worked", or explicitly as "have kept working".

Another example:

試験に向けて、まじめに英語を勉強してきた。
Shiken ni mukete, majime ni eigo o benkyo shite kita.
Toward the examination, I have kept studying English seriously.

Kimashita is the past tense of kimasu, which is the polite (a.k.a. masu) form of kuru.

Answer 2

Sometimes -ていく (te iku) and -てくる (te kuru) express "Aspect" of time. https://en.wikipedia.org/wiki/Grammatical_aspect

-ていく (te iku) is from Present to Future. See: https://japanese.stackexchange.com/a/39413

-てくる (te kuru) is from Past to Present.

How long have you worked here?
Koko de wa dorekurai hataraite kimashita ka?

Here きました has nothihg to do with physical movement, and it is 100% expressing "Aspect" of time.

ここでは、どれくらい働いてきましたか？

This question is asking: How long have you worked here (from Past to Present in time) to reach NOW ( this point in time ) ?

But the answer doesn't have to be specially-tailored for time. The question is no different from the usual [present perfect] form in English :

How long have you worked here?