[3] Then, he was invited to skate in the gala at the 2019 World Team Trophy as the reigning Japan junior national champion.

[9] Moving to the senior level permanently, Tsuboi was assigned to make his Grand Prix debut at the MK John Wilson Trophy, where he finished fifth.

[3] At his second event, the Grand Prix of Espoo, he was fifth in the short program but rose to fourth after the free skate, where he set new personal bests in that segment and overall.

[10][11] Tsuboi finished ninth at the 2022–23 Japan Championships, and was subsequently assigned to compete at the 2023 Winter World University Games.

[13] Given two assignments on the Grand Prix, Tsuboi finished eighth at the 2023 Skate America and ninth at the 2023 NHK Trophy.

Selected as a host pick at the 2024 NHK Trophy, Tsuboi placed third in both the short program and free skate, scoring personal bests in all competition segments.

During the short program, Tsuboi finished a disappointing fourteenth place after landing his quadruple salchow on the quarter and popping his triple axel attempt into a single.

Due to several skaters that placed ahead of him in the short program faltering during the free skate, Tsuboi managed to move up to the bronze medal position overall.