Hello, I stumbled upon this thread while lurking and registered because I have found something. I am pretty sure this is Yuzu's youtube account (99%)
I used the wayback machine and there was an entry for his youtube dated 2016. I think this image is selfexplanatory.
Yuzu liked Kendama videos around the time when he showed off his kendama skills. Not sure whether he liked them before or after his "performance". Hence why I think this has to be his account!