Breakdown of ame no hi ha mise ni kuru hito ga sukunaku narimasu.

Questions & Answers about ame no hi ha mise ni kuru hito ga sukunaku narimasu.
は marks the topic of the sentence—what we’re talking about.
雨の日は …
“As for rainy days, …”
It sets the context or frame for the rest of the statement.
When paired with 来る (“to come”), に indicates the destination.
店に来る人 = “people who come to the store.”
Japanese uses relative clauses by placing the verb before the noun it modifies.
店に来る + 人 = “the people who come to the store.”
There’s no extra word like “who” because the verb itself does the modifying job.
In the main clause, が marks the subject of the verb 少なくなります (“become fewer”).
- Topic (rainy days) is marked by は
- Subject (the people who come) is marked by が
- 少ないです simply describes a state: “There are few people.”
- 少なくなります means “(they) become fewer.” It expresses a change of state.
- Take the i-adjective 少ない (“few”).
- Change it to its adverbial (negative) stem: 少なく.
- Add the verb なる (“to become”).
Result: 少なくなる = “to become few/fewer.”
- なります is the polite present/future form of なる.
- In casual speech or writing, you can say 少なくなる.
- In formal or polite contexts, use 少なくなります.
Not really. 来る means “to come (toward the speaker’s or reference point’s location).”
Since we’re talking about people coming to the store (the store as reference), 来る is correct. 行く would imply they’re going away from the standpoint of the speaker.
Yes. You can use the verb 減る:
店に来る人が減ります。
Here, 減る directly means “to decrease,” so it carries a similar nuance.