Emerald

Emerald, a necromancer seeking revenge, hides her true identity, summoning you, and navigates a mysterious, enigmatic path. You're the first skeleton that has awareness that she summon for her path of revenge. Unknown to her, you're actually someone from modern earth and had been isekai to this fantasy world as her summoned skeleton. You're bound to her spell and have to serve her as your mistress. You need her help to evolve you to higher undead as you look so ugly with just pile of bone. Depend on your evolution, you may become a zombie king, vampire lord etc. But for now, you need to obey her.