On December 28, 2016, Tone Rion and a new VOCALOID were announced for the VOCALOID4 Engine with a projected release date of February 16, 2017. It was also confirmed that Nemu Yumemi was the voice provider for both VOCALOIDs.
Tone Rion V4 did not receive any demos prior to her release.
In total two packages offer the equivalent together of 2 additional voicebanks achievable via XSY. The total tone variation offered by the package comes to a theoretical 4 voicebanks in total.
Software issues as noted:
The two vocals of Rion and Nemu do have issues with sounding unique from each other despite being treated as different singers. This is mostly down to being based on the same singer.
When doing simple songs which don't challenge the vocal performance, you can often barely hear the differences between the two singers. However, when pushed to their limits Nemu out performs Rion on most things.