Nintendo today reported that all the Wii U production finished in Japan. It means you can buy the console (even the bundle version) until it is stock in somewhere but the company is not going to send out more shipments about the console in Japan.

The Wii U was in the mid-selling range on the Japan chart all the time. The online game which could keep alive the console in the country was the Splatoon but with the Nintendo Switch release (2017 March) it will be over since the Splatoon 2 comes only on Switch.

The Wii U at the moment costs 32 400 Yen in Japan but the new Switch release in March so if you are planning to buy a new Nintendo home console, wait for the Switch (except if you want a replacement one).
The current Nintendo lineup can be found in here: https://www.nintendo.co.jp/hardware/wiiu/lineup/index.html