Gankutsuou, 91 Days Recommendations
Aside from these series being stories of revenge against three people that ruined the lives of the respective lead characters, there does not initially appear to be too much linking the two: 91 Days involves 1920's American gangsters, where as Gankutsuou is a multi-layered 'dish best served cold' saga involving French noblemen. But, by the end, the 91 Days scheme for vengeance turns out to be more complex than it first appeared...
So, read the words of Edmond Dantes and understand: "Bide your time and hold out hope." Also, watch Gankutsuou. Now.
A story about a man going on a quest to get revenge against the people who ruined his life.
Both have great story. Both are filled with betrayal, murders and revenge. If you are looking for an adult plot without any fan service, with reasonable characters and epic ending, dob't hesitate just watch it.