Tsuihou Sareta Onimotsu Tamer, Sekai Yuiitsu no Necromancer ni Kakusei Suru - Ch. 10.1

[MangaDex]

 

[Coldlight]

Finally, some backstory on the female lead. I think it could still be her parent who sealed her there, unless they were somehow both weaker vampires than she is. Given they somehow can't see her while still alive maybe they're also sealed or somehow in some kind of captivity. Then again their parental bond isn't that strong or so she says.