I also loved Doki Doki! So reading that makes me very happy!
Regarding Koko, I tried to make each character more or less have their own personality and way of expressing themselves. English is not my main language, so I find it more difficult to express some things. Although I try to keep everything the same essence, of course.
I hope to improve on those aspects in the future as well, as I like the idea of making each character unique.
And about doing more with Koko, or in general, I would first need to think of something that I like enough to do it. Since to be honest, I try to create the visual novels that I myself would love to read, enjoy or catch my attention. (That's why I didn't expect so many people to like my stories either, haha.)
Thank you for writing to me!