Konyaku Haki kara Hajimaru Akuyaku Reijou no Kangoku Slow Life

Get ready for a high-energy prison comedy! Prince Elliott is engaged to Rachel, the daughter of a duke, but he has his eyes set on someone else. He decides to break off their engagement by accusing Rachel of a crime she didn't commit and throwing her in prison. Little does he know, Rachel has already heard about his plans...and she is thrilled! To her, prison sounds like a fun vacation with no lessons and no annoying servants. She is more than ready to laze about and live the slow life! Surrounded by all the comforts she could want, Rachel thoroughly enjoys everything the dungeon has to offer while tormenting the prince however she pleases! Her free and merry prison life is just beginning!

(Source: J-Novel Club)