Even the anime only covers the first three books (and leaves viewers with a decidedly wrong impression about the story). The manga has a ton of material after that to hit if it lasts.
Seems less a yandere lesbian trope and more the one about a crazed stan (regardless of gender or orientation). Which Japan needs to have its nose rubbed in a lot more than it has,
Most LNs don't ever get complete manga adaptations. (And even the ones that are planned to do so take an eternity. See Toradora, for one, or Pet Girl's author's more successful Seishun Buta Yarou.)