For the fourth game, Takumi wrote the scenario and took on a supervisory role. He had wanted the series to end with the third game, as he felt Phoenix had been fully explored and that his story had been told; he said that it is important to know when to end a story, that he did not want the series to become a shadow of its former self, and that he did not see any reason to continue it. Despite this, the spin-off series "Ace Attorney Investigations" was created, being directed by Takeshi Yamazaki and produced by Motohide Eshiro; Takumi returned to the series to write the crossover "Professor Layton vs. Phoenix Wright: Ace Attorney". He also directed and wrote "Dai Gyakuten Saiban", which was described as being the first entry in a new "Ace Attorney" series. He said that he has mixed feelings about the series being developed by other Capcom staff, comparing it to a parent sending their child to their first day in school. Yamazaki and Eshiro went on to direct and produce the main series entries "Dual Destinies" and "Spirit of Justice". Due to exhaustion after working on "Dual Destinies", Yamazaki split direction responsibilities with Takuro Fuse for "Spirit of Justice", with Yamazaki working on the scenario, and Fuse on the art and gameplay. In 2020, Yamazaki left Capcom.