Gankutsuou

In the year 5053, French aristocrats Viscount Albert de Morcerf and Baron Franz d'Epinay attend the festival of Carnival on the moon city of Luna. While Franz is just looking to have fun, Albert is seeking something more to fill his life—but he finds more than he bargained for in The Count of Monte Cristo, a mysterious and charming self-made nobleman who meets his gaze during an opera performance.

Through a few twists and turns, Albert befriends the Count and introduces him into French society. The Count, however, has more on his mind than just friendship; he plots to finally unleash his vengeance on those who wronged him years earlier. Gankutsuou follows Albert and the Count's intertwined destinies and the ultimate price paid for enacting revenge.

(Source: MAL Rewrite)