what's with the little corner in the sink? is that just a thing they have in japan?

It's a little garbage can for sinks. Used so that when you wash your plates and stuff, you dispose of any leftover food there instead of letting it clog up your sink.

So anon kept the wasa's braids but got rid of its paste core? That's definately the best option.

A surprisingly happy end for a yukkuri experiment story!