Looks like there's a bug transferring saves from 0.24 to 0.25.
In 0.24 the firstfight variable does not get set, so if you transfer to 0.25 after completing the relevant event, it causes a softlock for progressing Yuki's events.
Doubly confusing because the condition for Yuki's quest hint is reversed. So by having the variable set to 0, it's giving the hint for a trigger that only works when it's set to 1.