Honestly it's highly likely gonna be yuri and yaoi integrated, so it's better for you to stop reading after ch 1 because it's surely gonna be yaoi with the guy that goes to Tokyo probably being with another guy.
I genuinely just recommend reading "Cocoon Entwined", it's by the same author and though it's not about zombies, it has that same eerie-like story that makes you want to read more!
Plus it's Yuri only too because it's set in a girls-only school!
Oh okay, thank you for letting me know! Also I've already read Cocoon Entwined, it's one of my favourites, which is why I'm kind of disappointed with this manga ngl lmao.
Probably gonna get downvoted by a bunch of people for saying this, but someone PLEASE DM ME the list of chapters of ONLY YURI/GL when this gets completed, not wasting my time on waiting for new chapters just to be disappointed with yaoi/BL.