My friend group needs help deciding between traveling to Japan or Thailand

Me and 2 other friends really want to travel to southeast/east Asia. We have narrowed down our trip preferences to Japan or Thailand. The issue is we can't decide between the two.

With our budget we are closing between around 10 days in Japan or around 20-30 days in Thailand.

We are planning on going during late June to early July, so it will be in the middle of the rainy season.

I would really just like to hear peoples opinions on what we should do.

My group is really big into nature experiences, but one person really really wants to go to japan for the culture and experience.

We are too young to drink alcohol so the party scene in both countries is out of the question.

Edit- no one in my party is interested in alcohol either

If just wanted to ask yall what you would choose if you were in my situation