Tadashi has black hair, fair skin and wears glasses. He was seen in The Bow-Bow Grasshopper wearing a light olive green shirt and brown shorts.
Tadashi is a prankster. As revealed in the episode, he drew Gian and Suneo and blamed Nobita for it, and also played a prank on Shizuka, to see underneath her skirt. Additionally, he also cheated during the exams and schoolwork in order to earn high school grades.