Level 999 Kuromaku Koujo ni Narimashita

A girl from a poor family, suffering from a terminal illness, is given the opportunity to be reborn as any character she chooses. She mistakenly selects Raina Rubellite, the ultimate antagonist in the game "The Power of Love," instead of the character she intended. Reborn with immense dark magic abilities as the game's evil demon queen, she refuses to be bound by the game's predetermined story. Determined, she sets out to build the life she desires, regardless of her in-game role.