The main characters in both stories plays a game. These games are very similar. They both play the role of a guy in these mangas but they are actually girls.
Both mangas are related to virtual reality games, and a glitch that happened in the game. In 1/2 Prince, though, the main character, a girl, is a guy in the game. On the other hand, in Shitsurakuen, the main character, also a girl, is a girl in the game. However, both are wanting to save people, and both are strong and have many allies. However, 1/2 Prince has more comedy.
Fifteen-year-old Tsubasa's parents divorced three years ago, separating her from her beloved twin sister Arisa. However, they've communicated secretly with letters and are now meeting with each other for the first time since the event. Arisa is everything Tsubasa is not - she's popular, gentle, has good grades and has a new boyfriend, while Tsubasa can't seem to find girl friends to be cutesy with and has earned a reputation of being a delinquent leader. The two decide to switch places for a day and Tsubasa is enamored with Arisa's school life. But beneath the surface of Arisa's life lies dark secrets, not only about her classmates, but also Arisa herself. Tsubasa must infiltrate her beloved sister's life in order to discover the truth behind shocking events taking place...
Reading Shitsurakuen, I instantly thought of Utena. A female protagonist who wants to be a knight to protect girls, fighting for possession of girls, pulling weapons out of the girl's chests for the battle -- all of these elements are very similar. One of the major differences, however, is that Shitsurakuen is far more violent than Utena, darker in some ways. I was shocked at first, but if you like Utena, you'll probably find some value in Shitsurakuen (or vice versa).