I think it said she graduated 3 years ago, so it would probably make her around 21 years old? In which case this makes the story a liiiiiittle bit odd. Still like the overall plot tho!

The age gap does make things a bit awkward to know. I suppose it's still somewhat acceptable so long as she isn't old enough to be their mothers.

Anyways, more yuri villainess stories are welcome. Lady Lapis herself is so beautifully drawn, kind of reminds me of Shizuma from Strawberry Panic.

I... Wouldnt really call it acceptable. All 15 year olds I know behave pretty immaturely.