Iso dark gothicky romance mystery where an orphan girl (who has a scent or pheromones or unconscious odor that attracts men, and can occasionally turn them into hordes of crazed zombies who ravage & kill) is sent to live at a prestigious girl's academy through an unknown sponsor. An academy that's been plagued with unsolved murder cases, so that the ultra hottie military academy is stationed there too) the lt.general is interested in the orphans background & smell. At the academy, one of the girl seniors picks the orphan to live with (& I'm pretty sure this girl is a cross dressing guy who's investigating the murders too) and pretty much is also trying to seduce the orphan.... and competes withe military for orphans attentions.

The artwork is gorgeous, as are the pretty military cadets. The girls are too. The dress is gothic/military/dark etc.

The artwork is similar if not identical to Rozen Blood. Or even Junketsu + Kareshi.

Please help me find it 😲

Chouchou Jiken ?
I actually never read it so I can't say for sure but your ask reminds me of the summary