Shu Takumi joined Capcom in 1994 along with Hideki Kamiya. His first game was ', a 1995 video game adaptation of an anime of the same name. He was designated as a planner, and because the director was busy with multiple projects, Takumi had some freedom in his role. In the years that followed, Takumi came up with an idea for a detective game, though nothing came out of it at first. Takumi was later picked up by Shinji Mikami to work on Dino Crisis. However, in early 1997, the Dino Crisis team was temporarily redirected to help work on the ill-fated original version of Resident Evil 2. Takumi was then made director of the Dino Crisis project before being demoted to planner, being responsible for the first half of the game. He was then made director of Dino Crisis 2, and was able to maintain his position throughout the game's development. After the release of Dino Crisis 2, Mikami gave Takumi an opportunity to make whatever game he wanted with a small team of seven. He conceived of a detective-themed visual novel that would allow the player to input his or her deductions in some way. He thought of two ways to achieve this, one being a "joint reasoning" system in which the player would correct the deductions of a detective, and a court system in which the player, as a lawyer, would point out contradictions between witness testimony and evidence. His team began work on ', a realization of the latter concept. Phoenix Wright: Ace Attorney was originally intended for the Game Boy Color, but after being shown a demo of Mega ManBattle Network on a prototypeGame Boy Advance, development moved enthusiastically to the then-upcoming handheld. Despite being such a small project with only two programmers and two graphical asset developers, with Takumi taking on the roles of planner, director and scenario writer, the team managed to finish the game in ten months. The producer, Atsushi Inaba, liked the game so much that he requested that it be made into a trilogy. Thus, ' and ' were produced in 2002 and 2004, respectively, followed by Nintendo DS ports of the three games, which were released internationally. The 2007 game ' was the last entry in the main series made under Takumi, who went on to create the standalone title '. After the release of the Nintendo 3DS, Takumi came back as scenario writer for the crossover game'. Takumi was not involved in the development of ' due to concentrating his efforts on said crossover game at the time. He worked on a spinoff series of the Ace Attorney games taking place in Victorian London and incorporating the "joint reasoning" system that he had conceived all those years before, including ' and ', which were released in 2015 and 2017 respectively. Takumi also acted as a script supervisor for the 2016-2018 Ace Attorney anime series.
