Koichiro Iketani leads the Akina SpeedStars racing team and pilots a lime green 1988 Nissan Silvia K's (S13). He works at an Esso gas station alongside Takumi Fujiwara and Itsuki Takeuchi, frequently discussing cars. As team leader, Iketani takes great pride in the SpeedStars and shows genuine concern for all members, including rivals. His driving skills are competent but not outstanding; he specifically struggles with drifting techniques, experiencing fear during skids, though he actively strives to improve. After the SpeedStars are outclassed by the rival RedSuns during practice, Iketani attempts to keep pace but strikes a road bump, loses control, and crashes his Silvia.

Upon discovering Takumi Fujiwara is the driver of the legendary "Eight-Six," Iketani approaches Takumi's father Bunta to request he race for the SpeedStars. When Bunta declines, Iketani is surprised to later see Takumi arrive as their racer. After Shingo Shoji of the NightKids intentionally bumps Iketani's repaired Silvia during a confrontation, causing it to spin out, Iketani demands an apology, leading Shingo to issue a "Duct Tape Death Match" challenge against Takumi.

Iketani maintains a senpai relationship with Takumi and Itsuki at work and within the racing community, often watching out for them. He exhibits difficulty in romantic relationships, notably mishandling a potential relationship with fellow racer Mako Sato by jumping to conclusions and misunderstanding her intentions.

Preparing for Takumi's race against Ryosuke Takahashi, Iketani lends his Nissan Silvia S13 to Takumi for driving practice. That same night, Bunta Fujiwara tests new suspension modifications on the Eight-Six. Following the resolution of the conflict with Shingo and the NightKids, Iketani continues participating in team activities and supports Takumi's development as a racer.