Shuichi's talent as the Ultimate Detective is a fabrication made by Team Danganronpa. As shown in the final trial, Shuichi was a normal high school student who has no amazing talent such as Ultimate Detective whatsoever.
Shuichi is a very skilled detective, capable of solving a murder case faster than the police, although he claims he only managed to solve the case by chance. However, Kokichi Oma's secret society is so mysterious that even Shuichi does not seem to know any organization matching up with it.
As a detective, Shuichi has a keen intellect and is a sharp thinker. While he is timid when talking to others, he is seen to be calmer and firmer when analyzing and doing reasoning. He suggests that there might be a "mastermind" among the students simply by Monokuma's claims. By the first trial, he is able to reach the truth faster than anyone else, but is hesitant to say it because of his "fear of revealing the truth". However, he progressively gets more confident within this area as we progress ingame.