I think the mental change here is pretty well done. Ibuki comes across as a more active, self-confdent, and sex-hungry Darnell, which is basically everything he wanted to be pre-transformation. The transformation itself tamer compared to previous TGs of yours and their copious amounts of cum (both male and female). However, this works here since the change feels more tailor-made to Darnell's character. This isn't just some random transformation: Darnell was specifically chosen by Arata for some higher purpose. 

As a bonus, your lines during key parts of transformations are always a treat to read. Ibuki is quite the screamer