toilets:wash=* seems appropriate.

IMHO, the “integrated Japanese style” might as well be toilets:wash=washlet tag, per Wikipedia.

Again, Wikipedia suggests bidet (saved everyone a click: taps with a small sink) is slightly different than the usual bidet shower. I guess fancier toilet amenities might offer these kind of bidets (with sinks) rather than the usual bidet showers.

But then again, toilets:wash=shower gets the job done. For those special ones, might be toilets:wash=bidet.

Buckets? I reckon cistern (toilets:wash=cistern) might better fit the description for something like this. In short:

  • toilets:wash=cistern (with a water container)

  • toilets:wash=shower (the usual, ordinary cleaning option)

  • toilets:wash=bidet (for special sinks)

  • toilets:wash=washlet (Japanese-style)