[4] Ichiban is an orphan raised in Kamurochō by Jiro Kasuga, the manager of a soapland, a type of prostitution establishment that provides its services based on the exploitation of a loophole in Japanese law.

To Yokoyama, Ichiban's comical "fool" deliberately contrasts the dark setting of Like A Dragon, and that his most important role in the game is to overturning "worldly prejudices" and fight against "invisible discrimination".

[7] Following the worldwide release of Like A Dragon by late 2020, Nakaya indicated in an interview with Famitsu that Ichiban will lead the series for the foreseeable future, and that he was grateful for the support from Takaya Kuroda, Kiryu's voice actor, with regards to the transition.

He meets ex-detective Koichi Adachi, who explains that while Ichiban was in jail, Arakawa defected to the Osaka-based Omi Alliance and betrayed the Tojo Clan to the Tokyo Metropolitan Police.

Ichiban's investigation embroils him in a conspiracy involving a massive counterfeiting ring being run by the Ijin Three at the behest of a powerful Japanese politician, Yutaka Ogikubo.

After sighting a picture of Ryo Aoki, the upstart Governor of Tokyo and co-founder of Bleach Japan, Ichiban recognizes him as an actual living Masato Arakawa.

Ichiban learns from Seiryu Clan chairman Ryuhei Hoshino that the counterfeit bill is proof that Arakawa shot him in a non-lethal manner to create a false impression of his demise.

Ichiban and the Ijin Three leaders resolve to field a candidate they would endorse to compete with Bleach Japan loyalist Souta Kume's candidacy for the upcoming regional representative election.

Ichiban learns that Arakawa is a double agent, and that once the Omi chairman, Masaru Watase, is released from prison, he will make a joint announcement with Dojima to disband their respective clans.

Ichiban confronts Aoki during an election rally and tricks him into sending his men to the Millenium Tower at Kamurochō after lying about Sawashiro leaking the existence of incriminating evidence at the Arakawa Family office.

Ichiban appears as an unlockable player character of the promotional freeware game Streets of Kamurocho, developed and released as part of Sega's 60th anniversary celebrations in October 2020.

[14][9] A line of Yakuza franchise merchandise developed by apparel company SuperGroupie was launched in June 2021, including watches, bags, jackets, and shoes, all of which will have details inspired by Ichiban's appearances in the games.

[15] A cologne label titled "Ichiban Kasuga Eau de Toilette", which was developed as a collaboration with fragrance company Fits Corporation, was unveiled during the franchise's 15th anniversary live stream by Sega.

[21] Jorge Jimenez from PC Gamer praised Ichiban's optimistic characterization, a "goofy, happy go lucky gangster who loves classic JRPGs", as an effective way of explaining the franchise's drastic genre shift with Like a Dragon.

Chris Moyse from Destructoid praised Ichiban's character arc for "masterfully blending stoicism, bravery, pathos, heroism, and just the right amount of complete and utter idiocy to immediately win the hearts of the Yakuza faithful".

[24] German publication GamePro lauded Ichiban for his big heart and highly emotive nature, qualities which they feel a lot of protagonist characters lack.

[27] Hayes Madsen from Screen Rant said Ichiban is the most important protagonist in games for the year 2020, and called him an inspiring character due to his unfailing kindness and warmth of humanity, and that his story arc in Like a Dragon put forward meaningful commentary on the inequalities of society.

[28] Chingy Nea from Kotaku praised Ichiban as the Yakuza series' most relatable protagonist and one of its best characters, and the main reason why Like a Dragon was a source of comfort and joy for her in late-2020.