They have City League in China and similar team tournament in Korea. Why is it difficult to set up the tournament with the same format in Japan?
Maybe we will see it in the future, but it seems that nowadays Japanese Go has problems with finding new sponsors.

Just few examples:  Japanese World Cups - Fujitsu and Toyota&Denso recently stopped (they don't have any World cups anymore in Japan)
World Amateur Go Championship, sponsored by JAL (Japanese Airlines) was not stopped, but is organizing  in different countries now, after JAL refused to support it anymore.

Another example is the Haya (Blitz) Go Championship sponsored by Tokyo Television. Over the years it was scheduled earlier and earlier on Sunday mornings and fitted into a shorter and shorter format. In the end it was a 10-second per play fast game at 06 AM Sunday morning. This was not online but rather IRL over-the-board play at 10-seconds per play. It was painful to watch. Finally it was canceled about five years ago when Japan Airlines dropped out as sponsor.

The best decision can be sending Japanese single team to take part in Chinese or Korean League. It must be much cheaper and can be accepted even without finding a new Japanese sponsor