Taiga was originally an esteemed doctor at the Seito University Hospital until he had his doctor's license revoked after failing to save a patient and thus began operating as an unlicensed doctor.
He was portrayed by Ukyô Matsumoto.
Taiga was a revered doctor at the Seito University Hospital when Zero Day occurred and he was selected to be a Kamen Rider to combat the Bugster virus. Despite being approved to be a Kamen Rider, Taiga initially refused to become a Rider until the death of his coworker Maki spurred him to accept it.
However, the Proto Bang Bang Shooting Gashat soon began to have both mental and physical affects on Taiga, causing him to be temporarily prohibited from transforming. Still determined to save his patient's life, Taiga ignored orders for him to stand down and reclaimed the Gashat and Gamer Driver from Kuroto Dan, just as Kuroto planned. Taiga attempted to defeat Graphite, the Bugster who had spawned from Saki Momose, in order to save her. However, Taiga was unable to defeat Graphite, leading to Saki succumbing to Game Disease. For disobeying orders, the Ministry of Health revoked Taiga's doctor's license. Because Taiga had failed to defeat Graphite ans save Saki, Saki's boyfriend, Hiiro Kagami developed a grudge against Taiga, blaming him for Saki's death. Losing his hope in saving others as a doctor, Taiga decided that clearing games was the only important thing to him.
Second Bugsters Outbreak
After a second Bugsters outbreak occurred in the present day, Taiga began hunting down Bugsters again, often clashing with the other Doctor Riders due to his abrasive attitude and unwillingness to work with them. Learning that Emu Hojo was Patient Zero for the Bugster virus, Taiga attempts to take his Gashats from him without telling him the truth about it in order to keep his stress levels low, though this would prove futile when Kuroto Dan revealed it to Emu out of spite.
At the end of the show, after helping to shut down Kamen Rider Chronicle and save everyone trapped in it, Taiga was rewarded by having his clinic reopened as a legitimate one under the Ministry of Health and having an official doctor's license again.