Can a baito take 3 weeks off for travel?

Hi

I’m currently working part-time (baito) about 5 days a week and I pay taxes in Japan. I’m planning to travel around Europe for about 3 weeks. Usually I only take 1 week off when I travel, but since flights to Europe are expensive, I thought it would make sense to visit multiple countries while I’m there.

I mentioned it to a coworker and he said, “やめた方がいいよ、長すぎ。社長も怒る” (You shouldn’t, it’s too long. The boss will get mad). That surprised me a bit.

Since I’m paid hourly and not a full-time employee, I assumed my schedule would be more flexible. It’s not like they would be paying me during that time.

I also remember when I was a student during high-school people would sometimes take days or even weeks off just by saying they had school-related things etc and it didn’t seem like a big issue. So I’m a bit confused about whether 3 weeks is actually unreasonable for a part-time job.

Can a company refuse to let a part-time worker take 3 weeks off? Or does it just depend on the workplace? It’s not like we’re short staffed

And what would be the best way to ask my boss about this without causing problems?

I’ve also heard from a Japanese friend that sometimes long vacations for travel aren’t always viewed positively in some workplaces, and that people might react differently compared to taking time off for something like school or family reasons. I’m not sure how true that is, but it made me wonder whether I should be careful about how I explain the reason.

Thanks in advance.