Fuutarou Uesugi is the main protagonist of the series. He is a serious and hardworking high school student, and a prodigy at the top of his grade. Due to financial reasons, he is tasked to tutor the Nakano Quintuplets.According to Isanari, Fuutarou used to be similar to his father as a child, having a wild personality and being bad at studying. He currently lives a frugal lifestyle, preferring solitude. Someone comments that Fuutarou is always like this, trying not to associate himself with everything. Ichika comments that Fuutarou is direct and doesn't mince words. Yotsuba's first impression of Fuutarou is that he is a gloomy man and doesn't have many friends. His facial expression is always serious, sometimes he looks grumpy and annoyed, and he rarely blushes or gets flustered. Fuutarou thinks that being the Class Representative would only be hindering his studies.Fuutarou is noted to have a big ego and high confidence. He can also be rude and direct, but he is actually able to contain his emotions. Despite that, Fuutarou could momentarily lose his composure when agitated and faced with unfavorable circumstances. He also does not like to get involved with other people's problems, as they find it troublesome.Fuutarou has been shown to be very hardworking and has a lot of patience, as he is able to tutor several girls who have below average scores. It is personally stated and implied that Fuutarou currently has no interest in romantic relationships. He considers love as something silly.