Questions about example sentences with, and the definition and usage of "Oshima"

A: @samusan1 thanks for your help !

A: × I went to Oshima which there are many people come when some flower festivals going with my friends for a long weekend.
✓ I went to Oshima with my friends for a long weekend. A lot of people go there for flower festivals.

× We went to a zoo that only 4,5 people were and no one was in a festival place.
✓ We ended up going to the zoo. There were only 4 or 5 other people there, and no one was at the festival location.

× We were expecting that they are busy but it turned out not busy.
✓ We were expecting them to be busy, but they weren’t.

× I was like " Even on a place where people said busy doesn’t have people, how do they manage their island as a tourist spot."
✓ I was like "How do they manage their island as a tourist spot when barely anyone visits?"

I’m not sure if I understood your last sentence correctly, but what I wrote is natural and makes sense given the context. Try to review sentence structure and how to form proper complex sentences. That will help you with clarity and naturalness. You can also break up your sentences because you don’t have to fit everything into one.

A: "Oshima island in Japan is only full of deserts."