It's probably a rubber dome keyboard but it has scissor keys which suck to remove without breaking em. If you take it apart you can wash the rubber membrane with soap and water and wipe the circuit board with alcohol. Adding water will just make it less sticky but the water will stick around and probably corrode something eventually.
Surugaya and Hard off are pretty popular. I also saw someone do a video on Beep. Lotsa Japanese YouTube collectors road trip around going to Hard offs.