Hajime Iwaizumi

Iwaizumi is a stubborn but reliable teammate back in his high school days, 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 skills.

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" fish in a book to make fun of Oikawa with.