In 2012, he entered the first term of the Ishin Political School. When Kitagawa died in 2018, he announced his candidacy in the
by-election which occurred after. He ran against Tomokatsu's nephew, Shinpei Kitagawa, and former Opposition member
Shinji Tarutoko on top of JCP member
Takeshi Miyamoto. He won by nearly 8%, marking a gain for the party. In the
2021 Japanese general election, he won by nearly 20 points over Shinpei Kitagawa again. Once
Toranosuke Katayama resigned as co-leader of the party and
Nobuyuki Baba was appointed in his stead, the party chose to appoint Fujita as his replacement for Secretary-General. In the 2022 Ishin leadership election, he supported Baba. He has been one of the foremost spokespersons in Nippon Ishin no Kai. He has also been extremely critical of the ruling
LDP, stating that under no circumstances would Ishin form a coalition with the party, further saying that he would have to "see the election results before commenting on a coalition (with the
CDP)." After Ishin underperformed in the
2025 House of Councilors election, co-leader
Seiji Maehara and three other party executives announced their intention to resign. Fujita was elected to replace Maehara on 8 August 2025, serving as the party's chief representative in the National Diet while
Osaka Governor
Hirofumi Yoshimura maintains his leadership position. == Political positions ==