Wataru Akiyama

Wataru Akiyama (秋山 渉 Akiyama Wataru, known as Aki in the English localisation of the Arcade Stage games) was one of the first racers from Saitama to actually race against Takumi with his turbocharged Levin; he appeared later in the Project D arc, this time replacing the turbocharger with a supercharger for more linear acceleration and to avoid Turbocharger lag.

The New Eight-Six Arc
Wataru is a skilled driver who honed his skills on the treacherous Shomaru Pass. He came to Gunma in hopes of facing new racers to challenge, as well as to watch over his sister Kazumi, who just got a job at a hotel with her aunt. He was first seen appearing at Akagi to spectate the battle between Ryosuke Takahashi and Kyoichi Sudo. Later on, after finding out from Keisuke Takahashi that Ryosuke was defeated by another lone racer from Akina who also used an AE86, which was Takumi Fujiwara, Wataru decided to battle against him instead. Earlier he wanted to battle Keisuke at Akagi, but Keisuke declined since it was against the RedSuns's policy to race in their home turf. Still not satisfied, Wataru engages in an impromptu battle, with Kenta spectating behind them. Keisuke and Kenta soon realizes this was no ordinary 86, as they noticed from its speed and the engine sound, from which they understood it was turbocharged. The battle ended as they both skid to a halt from a crashed car in the middle of the road. Wataru vows to battle with Keisuke later on, with Keisuke looking for the same.

Soon Wataru meets Takumi with Itsuki's help, after knowing his sister was dating him. After Wataru checks Takumi's engine, after the former tells him that his car had been acting slow, Wataru nearly snaps out and gets angry at Takumi for thinking that Takumi was lying. After things gets de-escalated, Takumi explains to him that earlier engine blew up and he got an engine swap with this one. While Takumi was taking a ride in his car with Wataru to see the problem, Wataru quickly realizes that the problem was in the tachometer of Takumi's car, which was not yet changed.

After Takumi upgrades his car's dashboard instruments, and gets information from Bunta about the revs at which the gear should be shifted, Takumi battles with Wataru in Shomaru pass. They start the battle in a cat and mouse chase, as the course was too narrow. Exclusively in the anime, the SpeedStars and the RedSuns spectate the battle, with them explaining the differences in the two 86s and the quirks of Takumi's new N.A. engine against Wataru's turbocharged engine. As per each rounds, Takumi began to adapt to his new engine more, while Wataru observing him getting better each round, praises him for being his opponent. On the 5th round, while Wataru was on the lead, Takumi suddenly overtakes Wataru on a straight, where there was supposed to be a mudslide but after all rounds, its been mostly levelled. Takumi overtakes Wataru while going airborne for a bit while he crossed the slide. Wataru concedes defeat to Takumi.

Saitama and Ibaraki Arc
It is later on revealed that Wataru is Nobuhiko Akiyama's cousin, as seen when he watches Project D race against the Northern Saitama Alliance in the hopes of finding a weak spot. They later on meet up with Sakamoto, a rally racer at a restaurant where Nobuhiko analyzes Takumi's driving pattern, and introduces them to a kei car, Suzuki Cappuccino, to which Sakamoto will battle against the Project D. Wataru finally got his chance to battle against Keisuke in a wet-weather race, this time with his supercharged engine. However their battle drained on for some rounds, and as Wataru was on the lead, his tires lost grip upon touching a metal gutter while he adjusted his wipers, causing him to spin out while Keisuke passes him. He was defeated by Keisuke this time officially.

Wataru is seen later on when Kazumi's ex-boyfriend reaches out to him so that he can meet her one last time and confess his mistakes and true feelings her as she was ignoring him. Wataru takes him to a grocery store where Itsuki and Kazumi was, and tells Kazumi there's no point in running away from the past, so she has to face it. Kazumi falls for ex boyfriend, leaving Itsuki heartbroken. The next day, after Takumi finds out about Itsuki at the gas station, who was absent then, Wataru pulls up and apologizes to Takumi for her sister's choices, and tells him to ask Itsuki to find her better girls than her sister. Afterwards Takumi opens up about his "four-wheel drive complex", since he was defeated in Akina by an AWD car. Wataru gives advices about overcoming it, and about the next opponents Project D will face.

Kanagawa Expedition
Some time later, Wataru confronts the impostor Project D somewhere in Saitama and helps the real Project D expose them as the frauds they are. By that time, him and Keisuke had become close buddies, as seen by their responses.

He later watches the final race between Project D and Sidewinder along with Nobuhiko and Sakamoto.

Trivia

 * Wataru is present in MF Ghost, where he is presented as a commentator on the third round of the MFG.