Project Justice, also known as Project Justice: Rival Schools 2, and known in Japan as Moero! Justice Gakuen, is a 2000 3D fighting video game produced by Capcom as the sequel to Rival Schools: United By Fate (1997). The game was released on the Sega NAOMI arcade board and Dreamcast home console initially in Japan and globally in 2001. Like its predecessor, it revolves around team battles between students of different schools and is set one year later, but teams now have three fighters instead of two and a new move mechanic called Party-Up is introduced. Project Justice received a favorable reception.

Project Justice's fighting system is lifted from the original Rival Schools, with some notable changes. The game continues to be a team fighter, but has teams of three characters instead of two. This allows another Team-Up attack to be used in a fight, but also adds a new type of attack, the Party-Up, initiated by pressing any three attack buttons. The Party-Up is a three-person attack that varies based on what school the character initiating the attack is from.

The additional partner also allows players to cancel an opponent's Team-Up Special by inputting a Team-Up command of their own. This initiates a short fighting sequence between one character from each team. If the person initiating the sequence gets the first successful hit in during the sequence before time runs out, the Team-Up they are caught in will be canceled, and the game switches back to the main fight; if the opposing player gets the first hit or time runs out, the Team-Up continues as usual.

Additionally, the "vigor" meter in Project Justice is limited to 5 levels (down from 9 in Rival Schools), with Party-Ups requiring all 5 levels, Team-Ups continuing to cost two levels, and any attempts (successful or not) to cancel a Team-Up costing one level.

Also carrying over from the first game, the Dreamcast port of Project Justice in Japan includes a character creation mode that allows a player to create their own fighters who can be used in all modes except for single-player. However, the character creation in Project Justice is packaged as a board game, taking place during an inter-school festival, rather than a date sim game like in Rival Schools. As with School Life Mode in the original Rival Schools, though, this boardgame is not included in non-Japanese ports of Project Justice due to the amount of time it would take to translate the mode. Instead, several unlockable sub-characters were included in these ports, built from the character creation parts in the Japanese version.

All of the playable characters from the previous Rival Schools game return, with the exception of Raizo Imawano and guest character Sakura Kasugano, though the former appears as a non-player character in the game's Story Mode. Five new characters are introduced, along with alternate versions of a few existing characters.

As in the original game many of the characters use their chosen field of academic or sporting excellence as a fighting style. As a result, special moves - in particular the Two-Person team up moves - tend to have a surreal edge, with methods to injure your opponent ranging from: forcing them to take part in an impromptu bout of synchronised swimming (on dry land) (if Nagare is in your team); confusing them by taking photographs of them in rapid succession during an interview for the school newspaper (if Ran is in your team), or even berating them so severely that they fall unconscious out of shame.

Project Justice's single player mode was structured differently from its predecessor. While Rival Schools only plays a story if characters from the same school were selected, the game instead has separate Story and Free modes.