Japanese like "corner".

I'm in a restaurant now. I'm sitting on the right side table. The left and the middle tables were vacant. A man came and sat in the middle table!! Why?!?!

It might not be strange in other countries and for non-Japanese but it's quite strange for us Japanese.

Japanese tend to avoid sitting beside an unacquainted person. If ONLY the middle table is vacant, everyone sits in it of course. But both the left and the middle tables were vacant, in this case, almost ALL Japanese sit in the left table. The same applies to sheets in the train.
That's why I felt it strange.

Besides, he is a suspicious action. He is talking to himself and sometimes looking at me. I'm a bit scared.

By the way, if every table were vacant? Japanese also sit in the side (corner?) table. The same is also true of sheets in the train, benches in parks and so on.

Japanese seem to prefer corner. In fact it's more comfortable than sitting in the middle place.