Oozumou Reijou

When Floortje is reincarnated into the world of an otome game, things immediately go wrong. Her fiancé, Prince Jonas, breaks off their engagement, and the supposed protagonist, the Saint of Light Jaromíra, makes Floortje out to be the villainess. Little do they know, however, that Floortje was a sumo wrestler in her past life—and she won't let these weaklings stand in her way! After rescuing the cat-eared Prince Richie from the castle's dungeon, Floortje embarks on a journey with an ever-growing sumo stable to save the kingdom from the grips of the real villains, Prince Jonas and Saint Jaromíra. With the spirit of sumo—her most trustworthy ally—to guide her, she's ready for a smackdown! But why was she reincarnated into an otome game, and how did its protagonist turn evil in the first place?

(Source: J-Novel Club)