Because Nikki was an optional character in the game, sadly this is pretty much the extent of what the internet has to offer.

Official Images

These are the few images I managed to find through random searches.

The official character drawing
Right before his performance
During his performance ①
During his performance ②
During his performance ③
A Nikki keychain


These are really old and extremely somewhat embarrassing, but due to the lack of images above we'll leave them up for Nikki's sake.

This used to be on the index
A quick doodle