Hajime Iwaizumi (Japanese:
Iwaizumi has dark, spiked-up hair and slightly thicker than average eyebrows. His eyes are dark brown in the manga, olive green in the anime adaptation, and grey in the Haikyuu!! smartphone game. His hair is black in the manga and in the Haikyuu!! smartphone game, but dark brown in the anime. More often than not, he's shown to hold a serious or irked expression.
While playing volleyball, Iwaizumi wears a standard Aoba Johsai uniform with number four on it. He is otherwise shown wearing an Aoba Johsai school uniform consisting of khakis with dark brown details, a lavender-colored button-down shirt, a dark red tie, and a white blazer. Iwaizumi's uniform appears to be missing the cream-colored vest that goes with the rest of the uniform and appears to be slightly disheveled, with his tie loose around his neck and his shirt left untucked.
In the anime adaptation, Iwaizumi is seen wearing an outfit which consists of a pair of jeans with an oversized dark blue denim jacket over a grey hoodie.
Iwaizumi is a stubborn but reliable teammate, often filling in Oikawa's spot as a morale booster if needed. He acts supportive to all, including Tobio Kageyama, and calls Oikawa out for his childish antics. He often resorts to violence with Oikawa whenever he teases or provokes him, but this does not change the fact that he cares immensely for him, as shown when he makes an effort to stop Oikawa from either working too hard or losing confidence. Iwaizumi's firm-yet-caring attitude has led some members of the Aoba Johsai team to look up to and respect him. His underclassmen often gravitate towards him and he is seen giving calm and light-hearted advice to Kindaichi, which can contrast to how he treats Oikawa. He is also very respectful and does not treat his rivals coldly, as Kageyama still treats him respectfully and Iwaizumi has acknowledged his skill.
It is also seen through some extras by Furudate that while Iwaizumi can be strong and intimidating he also has quite the goofy side where he loves monsters and gets excited when he finds an "Oikawa" (a type of fish) in a book to make fun of Oikawa with.
They were both bitter rivals of Wakatoshi Ushijima, although Iwaizumi didn't seem to take him as seriously as Oikawa did. Iwaizumi constantly kept his friend in check, including the time Oikawa almost hit Tobio Kageyama. He often uses violent and somewhat harsh words to Oikawa but despite all that he still strongly cares for Oikawa. Iwaizumi and Oikawa later attended Aoba Johsai High together, becoming Vice-Captain and Captain respectively by their third year.
Karasuno High Team Formation Arc
Iwaizumi plays in the starting line-up in the practice match between Aoba Johsai and Karasuno. He is initially surprised to see Kageyama on the Karasuno team. Since Oikawa was not there for majority of the match, Iwaizumi acted as captain and kept his team together when it seemed like Karasuno was getting the better of them.
In the Interhigh preliminaries, Iwaizumi's team faced off against Karasuno High. In the end, Aoba Johsai advanced, but only to be defeated in the next round by Shiratorizawa Academy. While most 3rd years from other various schools moved on and left the volleyball club behind after the Interhigh, Iwaizumi and the other 3rd years stuck around to have another chance at beating Shiratorizawa.
Tokyo Expedition Arc
Spring High Preliminary Arc
In the Interhigh preliminaries, Iwaizumi's team faced off against Karasuno High. In the end, Aoba Johsai lost against Karasuno, thus finishing Iwaizumi's high school volleyball career. However, he returned to watch the Shiratorizawa vs Karasuno match, and he ended up watching the match with Oikawa whom he found doing the same thing.
During his sophomore college year of studying sports science, Iwaizumi had traveled to Irvine, California for a meeting with Takashi Utsui. While on his way to the meeting, he ran into Ushijima and explained that he was there hoping to intern under Utsui once he graduated college. It was then that he learned Utsui is Ushijima's father. After the meeting, Iwaizumi and Ushijima spoke about Ushijima's performance on the world team and the two looked over video's together. Before they parted, Iwaizumi requested they take a photo together so he could send it to Oikawa.
As of 2021, Iwaizumi is now an athletic trainer and is last seen with the Japan Men's Volleyball Team at the Olympics.
Iwaizumi is Aoba Johsai's ace, and his spikes are incredibly strong. He is a dependable player with faith in his own abilities, which leads Oikawa setting to Iwaizumi whenever he feels that he's in a pinch. He is shown to have solid receives; often getting the ball when Shinji Watari, Seijō's libero, is unable to. Iwaizumi stated that when he was little he only found spiking to be fun, but as he has gotten older he's grateful that he knows the "thrill" of receiving his opponents' flawless hits. It has been noted by Keishin Ukai that Iwaizumi has a powerful serve. Being hit continuously by his and Oikawa's serves throughout a match can be incredibly taxing on their opponents. He is also fearless enough to exploit Koganegawa's technical flaw as a blocker despite his height.
Jumping Reach: 327 cm
Aoba Johsai High
- Tōru Oikawa: Oikawa and Iwaizumi have been best friends since childhood, Oikawa dubbing the latter "Iwa-chan". Due to knowing him so long, Iwaizumi is one of the few who is able to tell when Oikawa is genuinely happy and not faking it for show and is able to tolerate his nonsense for the most part. Though Iwaizumi often insults Oikawa (dubbing him "Shittykawa","Trashykawa","Assikawa" , "Crappykawa", "Kusokawa","Lazykawa", "Loserkawa", "Dumbass".) and the two bicker, they work together brilliantly on the court and are completely in sync. Oikawa tends to toss to Iwaizumi if he feels as if he's in a tricky situation. Iwaizumi is often the one to keep Oikawa in check and drag him away from fangirls, much to the latter's dismay. Though Iwaizumi often lashes out at Oikawa for his stupidity, he genuinely cares about him and his health, as shown by him consistently reminding Oikawa to take breaks and not overdo himself. Iwaizumi hates it when Oikawa undermines himself, and angrily reminds him "you're a setter, aren't you!" when Oikawa insists that Kageyama was better at tosses.
- Takahiro Hanamaki: Hanamaki and Iwaizumi seem close, though the former is concerned about beating the latter in arm wrestling. He seems to wish to surpass Iwaizumi in strength. He likes to watch (or even join in with) Oikawa teasing Iwaizumi, or the other way around.
To himself, Season 2 Episode 25
- Favorite food: Agedashi tofu
- Current concern: "Just 1cm more..or 7mm, at least..!" (In regard to his height.)
- He is the oldest in Seijō out of all the members whose birthdays have been revealed.
- He is very athletic as shown by him beating Kyōtani in several events such as running, batting, and arm-wrestling.
- His star sign is Gemini.
- When combined, Iwaizumi and Oikawa's first names (Hajime and Tōru respectively) form "一徹" meaning "obstinate" or "dauntless".
- Iwaizumi's birthday is the death date of Alexander the Great, matching with Oikawa's birthday which is the birthdate of Alexander the Great.
- Iwaizumi is one of the few characters whose color palette varies in the manga to anime. In the manga, his hair is black and his eyes are dark brown, but in the anime, his hair is dark brown and his eyes are green.
- Iwaizumi's skills have been commended by Karasuno's players and coaches and his total stats add up to the same total as Ushijima, one of the top 3 aces in Japan.
- It has been confirmed in Chapter 395 of the manga that Iwaizumi and Oikawa are attending different universities.
- While Iwaizumi is taller than average, he's the shortest of the Seijō third years and appears to find frustration in this. In the Haikyuu Cross Team Match game, Iwaizumi states his goal is to grow to 185 cm so he'll be taller than Oikawa (who responds that he will push on Iwaizumi's pressure points so he can't grow taller than him).
- There is a running gag that whenever he and Oikawa are in the same camera shot, Oikawa will block Iwaizumi's face somehow, whether it be him holding a peace sign in front of him, or standing directly in front of him.
- Iwaizumi was voted the top wing spiker by readers in the "Best Lineup" poll with 1240 votes.
- In the Cross Team Match game, Iwaizumi says he used to capture cicadas during childhood but he always let them go afterward (when asked, he said cicadas had a short lifespan so he took pity on them).
- He's not very good at drawing.
- In Haikyuu's first popularity poll, Iwaizumi placed 11th with 3,097 votes. In the second, he rose to 9th with 6,111 votes.
- Hajime (一) - One
- Iwaizumi (岩泉) - Rock (Iwa) Spring/Fountain (Izumi)