Seiji Iwaki

Seiji Iwaki (岩城 清次 Iwaki Seiji, known as Hawk in the Tokyopop version) is the number two driver in the Lancer Evolution-only Emperor team, driving a Lancer Evolution IV. Seiji is a driver with good racing skills, but he is rather arrogant and occasionally imprudent. He has won many races driving for Emperor against other teams, including Takeshi Nakazato of the NightKids.

Emperor Arc
Back when Team Emperor appeared in Gunma prefecture to challenge the local racing teams, Seiji was sent out against every single opponent. He is known to have easily defeated a 180SX from Team Thunder Fire and Takeshi Nakazato from the Myogi NightKids, among others, taking each car's team sticker afterwards, cutting it in half and placing it upside-down on the side of his Evo's rear wing, similarly to how fighter pilots would paint kill marks on their planes.

After defeating various teams in Gunma, the Emperor team then set their sights on the Akina SpeedStars, aiming to beat Akina's infamous Eight-Six. Seiji volunteered to race for the Emperor team in his Evo IV against Takumi's Eight-Six. Kyoichi was well aware that Takumi could not be taken lightly and ordered Seiji to follow "Simulation 3", a plan used only when victory was not certain. Simulation 3 translated to "stay behind opponent, and overtake near the end before reaching the finish", but he was humiliated when he disobeyed Kyoichi by overtaking Takumi too early and eventually lost, leading to him being slapped by Kyoichi for his disobedience. Kyoichi then scolds Seiji for having lost the race and tells him to use his head and stop acting foolish, as Kyoichi now had to deal with the Eight-Six before the team could move on to their next opponent. Seiji then raced against Keisuke Takahashi on Akagi, and lost.

It was also verbally stated that Seiji lost to Kai Kogashiwa on Irohazaka, but no actual battle was shown in the series.

The New Eight-Six Arc
Seiji was a spectator for Takumi Fujiwara's race against Kai Kogashiwa at Irohazaka.

Exclusively in the anime, Seiji and Kyoichi also watched Takumi Fujiwara's rematch against Ryosuke Takahashi at Akagi, commenting on their driving skills.

Tochigi Arc
Seiji and Kyoichi came to Tochigi to spectate the battle between Takumi Fujiwara and Tomoyuki Tachi.

Kanagawa Arc
Seiji, along with Kyoichi, came to spectate Takumi's final battle with Shinji Inui in Kanagawa. After Takumi won, he and Kyoichi congratulated him on his victory.

Kyoichi Sudo
He is his best friend with whom he helped to create Team Emperor. Kyoichi helped establish confidence in him through having him race with different strategies. But after his race against Takumi, he was slapped as he disobedience of the Simulation 3 strategy resulted in defeat.

Itsuki Takeuchi
During their scouting in Akina, Seiji asked Itsuki for directions. After Itsuki gave him directions, he asked him who was the fastest driver on Akina. He mocked him for his answer, doubting an old Eight-Six wouldn't be worth a challenge. However, he was later convinced by Kyoichi to race Takumi later on after Kyoichi heard about Ryosuke's loss to him, confirming Itsuki's answer.

Takeshi Nakazato
Before he raced Takumi, Nakazato was his opponent on Myogi. Their race was a hillclimb, and Seiji defeated him with ease using Simulation 3. Nakazato surrendered his Night Kids team sticker to him as part of the deal of the outcome of the race. Takeshi was disgusted with this after his loss.

Takumi Fujiwara
Seiji first encountered Takumi on Akina when Itsuki confronted him. At that time, he was oblivious to the fact that he was Akina's fastest. When Emperor went out to face the SpeedStars, he came to realize it was him. He lost to Takumi in a downhill race as he disobeyed Kyoichi's Simulation 3 strategy, resulting in Takumi overtaking him at the second-to-last corner, for which he was slapped by Kyoichi. However, when Kyoichi beat Takumi on Akagi after the latter's engine blowout, he sort of pitied him, as he stated that he wasn't satisfied with Kyoichi's victory.

Keisuke Takahashi
During their invasion of Akagi, Keisuke was first in line to race Seiji before Kyoichi's race against Ryosuke. The race was a hillclimb, and Seiji was overtaken in the S sections of Akagi and lost. This battle was exclusive to Battle Stage.

Kai Kogashiwa
Prior to Takumi's rematch against Kyoichi, Kai Kogashiwa defeated him on their home turf.

Trivia

 * In the Funimation dub of Third Stage, Kenji says Seiji's name in the Japanese name order (Iwaki Seiji), instead of the English name order (Seiji Iwaki).