Rebirth in Another World as the Undead Queen

System: Ding! Congratulations on inheriting four Dark Altars and becoming the Lord of Darkness!

Serea: Huh?

System: Ding! Suitable vessel selected. Implanting in progress…

Serea: Hmm?

System: Ding! You have obtained your initial class — Blood Queen (Blood Altar), and gained your basic building unit — Blood Well!

Serea: Wait a minute!

System: Ding! You have obtained your second class — Undead Queen (Death Altar), and gained your basic building unit — Plague Graveyard!

Serea: I said wait a second!

System: Ding! You have obtained…

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In short, this is a story about a girl (very mysteriously, of course) who casually inherits four dark altars and is thrown into another world by an unscrupulous system.