Oujisama, Kore wa Gohoubi dewa Arimasen!

Sharon, reincarnated as the villainess, abandons the role of the evil woman and lives the life she always wanted—cuddling with her beloved dog. But suddenly she ends up saddled with 10 billion in debt. The condition for repayment? She must break her engagement with Prince Michael while playing the villainess. However, the prince, now a do-M loyal "dog" type, starts pushing for marriage... A wild school rom-com begins!

(Source: Kadokawa, translated)