Raika Koshiba, a member of the Corporate Youth Team "Tirnanog Youth," approaches cardfighting with a rational mindset, meticulously researching before every match. This analytical nature defines his strategic style. He strongly admires Michiru Hazama as an idol.

Within "will+Dress" Season 3, Raika aligns with the Uniformers faction, which advocates discarding individual identities and past connections to achieve greater strength through uniform appearance and mindset. He actively participates in the Uniformers' conflict against protagonist Yu-yu Kondo and Team Blackout, who passionately oppose the faction's ideology for devaluing personal journeys and relationships.

During this conflict, Raika faces Yu-yu in a cardfight. His defeat serves as a catalyst, prompting him to re-evaluate the Uniformers' principles. He begins questioning the validity of abandoning one's past identity solely for power, particularly challenging the methods and beliefs of Uniformers leader Gui. This loss marks a point of potential development regarding his perspective on strength and individuality.

Raika fights using the "Skyfall Executors" deck. A specific card associated with him is "Will+Dress Season2 Raika Koshiba," a Keter Sanctuary Trigger Unit (Grade 0) featuring Front Trigger and Shield boosting effects, also regarded as "Bard of Heavenly Song, Alpacc".