Tensei Maniana Reijou wa Yankee Denka ni Go Shuushin

Isekai Reincarnation Enthusiast Lady Is Obsessed with the Yankee Prince / Sixteen-year-old Martina is a count's daughter who adores isekai reincarnation novels. She is engaged to Rudius, the second prince of the Kingdom of Alzrite. However, Rudius is a shallow womanizer. Martina has no love for him at all; longing for true romance, she spends her school days eagerly waiting for their engagement to be broken off. Then one day, Rudius undergoes a sudden and dramatic transformation. His long hair becomes short. His neatly worn uniform turns sloppy. He starts walking bowlegged. His sharp eyes glare menacingly at everyone around him. He even rides off on a stolen warhorse! "I've regained the memories of my previous life from another world. You bi***, our engagement is over!" Martina is suddenly informed by Rudius, who claims to be a reincarnator from another world, that their engagement is canceled. But for someone like her, who absolutely loves isekai settings, this is more than welcome!