I would suggest, Maciamo san, that you let this one run free for a while. It most evidently stands that you have twisted the theme a bit, and have attempted to force changes mid-stream.

I put off posting here purposely. Some good comments and observations, in their various degrees of relativeness and correctness, have been put out on the table along with their opposites. The title to this thread makes a positive assertion, namely, that Japan does not have four seasons, and that Japan does not have biodiversity. Firstly, universally acceptable working definitions should be decided on as to what makes four seasons, and then a model against which to compare the degree of biodiversiy. (which you did, Maciamo)

However this has nothing to do with cultural comparisons, which I say is fair enough, only, then we have to allow room within the discussion for wide sweeps, seemingly off topic even, to build arguments to prove or supply evidence for a point.

I say Japan has four seasons, in different ranges of length and degree, but never the less a universally agreeable on four.

When compared to Saudi Arabia, yes, Japan has great biodiversity.