Visa for volunteer work exchange?

Hello guys :)
I'm planning on travelling Japan while doing some volunteer help exchange (Workaway, Helpx). The work is mostly helping with cleaning the hostel/Guesthouse and is completely without salary. So in exchange for helping out I only get free accommodation.

I'm sure some of you have heard of it before, therefore I wanted to ask you about the visa needed for such volunteer work? I have a hunch that visa waiver/tourist visa would be enough, but I'd like to be absolutely sure before I plan my trip any further. :)

I would also like to hear about your workaway/helpx/wwoofing experiences! :)

What is your citizenship and how long do you intend to stay in Japan?

I am a Finn and I've been in Japan on a tourist visa before. This time I'm planning to stay for 2 month.

Then just enter visa-free, no problem as long as long as you don't do paid work.

Thank you for answering :) That's a relief.