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.

Self-professed home security guard Mahiro Oyama has not left his home in years, secluding himself in his room playing erotic visual novels. This depraved lifestyle causes his prodigious sister, Mihari, to worry about his well-being. In hopes of solving this problem, she devises a plan to rehabilitate him back to normalcy. The first part of Mihari's plan is to concoct a medicine that changes her brother's biological constitution into a bona fide female, much to Mahiro's vehement dismay. Stuck in this predicament, Mahiro has no choice but to live out his life as a cute girl until the effect wears off—if it ever does.

Some time ago, the influential and powerful Toue Inc. bought the island of Midorijima, Japan, with the plans of building Platinum Jail—a luxurious utopian facility. Those who are lucky enough to call it home are the wealthiest citizens in the world. The original residents of the island, however, were forced to relocate to the Old Residential District; and after the completion of Platinum Jail, they were completely abandoned. Rib and Rhyme are the most common games played on the island. Rib is an old school game in which gangs engage in turf wars against each other, while Rhyme is a technologically advanced game wherein participants fight in a virtual reality. To be able to play Rhyme, you must have an All-Mate (an AI that typically looks like a pet), and the match must be mediated by an Usui. Aoba Seragaki has no interest in playing either game; he prefers to live a peaceful life with his grandmother and All-Mate, Ren. However, after getting forcefully dragged into a dangerous Rhyme match and hearing rumors about disappearing Rib players, all of Aoba's hopes of living a normal life are completely abolished.

High school students Yuma Okazaki and Hotaru Mizushina are childhood friends. With their respective boyfriends, Takeda and Fujiwara, their lives couldn't be more perfect. From playing in school to going on group dates, it seems nothing can break their bond. However, during one such group date, Hotaru makes an unexpected move. While Takeda and Fujiwara are distracted, she begins stroking Yuma's thighs. Taken aback by this peculiar action, Yuma awkwardly retreats to the toilets, followed shortly by her aggressor. Now in private, Hotaru forces the innocent Yuma into a locked cubicle and whispers into her ear: You'll be more nervous with a boy; I'll help you practice.