I presume that there is.

@Garban So there has to be a real sink nearby?

@JackPedigo, @Garban,

The toilet review site, Toilet Found! noted that the toilet-sink systems became popular in Japan after World War II when the real estate came with a hefty price tag. The design was meant for small bathrooms and living quarters, where creativity and innovation were key to comfortability. In addition to space constraints, the system also conserves and reuses water and does not require a heater to warm the water, potentially lowering utility bill expenses as well.

“The design is such that water from the supply line channels through the faucet for you to wash your hands. And then drained out through the sink drain and into the tank. The water will keep flowing to fill up the tank, until it gets shut off by the float,”

[toiletfound.com]

@Garban Oh, OK. That is a Japanese toilet-inspired application.
Here is a real Japanese toilet with a built-in sink.

@Garban My understanding is that you go to the toilet, flush it and wash your hands at the same time.This Japanese toilet design is for this single purpose only.

They use similar, only metal, in some prisons.