Game
Yumiko's challenge (not to be confused with a problem) is that she is the first Asian Darkhound ever made.
She is more of a unique prototype than anything else.
Her content is defined by being a side character and to some degree a very early staff prototype too.
The proto combos makes her hard to predict.
Sex? She is herself highly sexed, so probably, at some point, when or where it suits.
Daz (not game)
Here one could of course ponder whether a prototype remake, Yumiko ver. 2022, is an option to "reroll" her fate.
But,
(1) Good Asian assets are rare, so their evolution is not entirely likely to produce the "same" girl ex. Yumiko version X might not produce "Yumiko"
(2) Remakes need to be really good, they take a lot of time.
So Yumiko is a possible (due to prototype) but not obvious (due to asian) candidate.
Her current evolutions are also a good practical example of it.
Yumiko Evolution, early Akari branch
Yumiko Evolution, Late Akari branch
Yumiko Evolution, Akari Sakura branch
So they tend to turn into new girl types (when I tinker that is)
Note.
Summer and nothing else was happening so I felt like thinking out loud a bit on the Daz side of Yumiko evolution since she was mentioned. This is just a Daz walk through where Yumiko thoughts lead me over time.
The usual Darkhound decides the game disclaimers applies for anything related to the game itself.