Tadashi is a technological genius who turned down early admission to Harvard and a job working at Facebook when he was 14. He eventually started working for Raymond Reddington by the time he was 15, much to the disapproval of his mother.
Reddington visited Tadashi in his house with Dembe Zuma and Elizabeth Keen so he could analyze Robert Navarro's robotic glass eye for clues. Tadashi finds a chip that was manufactured by Wandtech which, to everyone's horror, specialize in making tracking devices and the eye is transmitting their location. Tadashi's mom walks in and they all here footprints upstairs and flee out the back to avoid Ian Garvey and his men. In Reddington's suite, he offers to put them up at a hotel until it is safe to go back home while Tadashi continues working on the glass eye, which he was able to disable. Tadashi successfully reverse engineers the signal and gives Elizabeth the location.
Elizabeth contacts Tadashi for help in breaking her colleagues out of Post Office after they are arrested by Homeland agents led by Anna McMahon on trumped up charges. Tadashi manages to guide Elizabeth through getting them out of their respective cells and guiding them out, while he is at the prom with his date. When they are caught as part of the plan, Tadashi loops the surveillance footage with Aram Mojtabai's guidance and then directs Reddington and his team to the Box and breaks them out and they all escape.