Koji is a tall young man of a wide, muscular build with peach-colored skin. His head takes the form of a rock, which is unevenly shaped and pointed at the top of his head, and his jaw is square-shaped.
His hero costume is a tight yellow suit, only reaching to his knees and elbows, with a large red marking over his torso and at the ends of his sleeves. On his chest, there's a symbol resembling an open mouth, and he wears yellow shoes with red lining.
In preparation for the Provisional Hero License Exam, Koji added two white straps over his shoulders and wears a mask that covers his entire face, with holes above over his mouth so his voice still can be heard when he's using his Quirk. His shoes were swapped out in favor of boots.
Contrary to his powerful and brutish appearance, Koji is a very shy and quiet person. As such, he rarely speaks and prefers using sign language to communicate with his classmates, so much so that Kyoka Jiro assumed that he was mute and was greatly surprised when Koji spoke. According to Fumikage Tokoyami, he is very good at keeping secrets. He also hates violence due to his kind-hearted nature.
He appears to enjoy the company of animals, even owning a small rabbit as a pet. With his Quirk, Koji can interact with them in ways others can't. He also owns a few animal dolls and decorations in his room, implying that he likes cute things.
Koji suffers from entomophobia, being deathly afraid of bugs, with the mere sight of them making him scream and run away in fear. However, Koji is capable of putting this fear aside if it means helping his comrades as was shown during the Joint Training arc when he attempted to use bugs alongside Kirishima to take down Jurota Shishida.
Overall Abilities: Thanks to the handling he has his Quirk, Anivoice, Koji is a rather versatile hero due to the diversity of abilities found within the animal kingdom. For example, bugs are able to perform sneak attacks from underground thanks to their small size and burrowing capabilities, birds are useful for reconnaissance due to them being flying creatures with great eyesight, etc. And despite Koji's generally shy nature, he is able to work very fluidly in a team of humans and animals alike, showcasing his multifaceted camaraderie.
Koji's control over animals proved vital and successful in various situations such as the First Term Final Exam, wherein he and Kyoka Jiro were pitted against Present Mic, as well as the first stage of the Provisional Hero License Exam, in which he used a large flock of birds to swarm numerous students from rival schools. During the first round of the Joint Training Battle, him and Eijiro Kirishima launched a collaboration attack on Jurota Shishida of Class 1-B that forced the latter into evading the said assault, implying their combined onslaught would've been effective against someone of his caliber. Soon after, Jurota dubbed Koji as troublesome due to the Petting Hero's abilities, so the feral student decided to capture him first. On Nabu Island, Koji used his control of birds to help Mezo Shoji rescue Mahoro and Katsuma Shimano from Nine. His abilities eventually garnered the attention of Wash, giving Koji the opportunity to intern under the No. 8 Pro Hero, and improve his communication skills.
- Enhanced Strength: Koji, befitting his bulky stature, possesses a fair amount of physical strength. During the Joint Training Battle, Koji was restrained and hauled away by a Beast-transformed Jurota Shishida, but his struggling made it difficult for Jurota despite the latter's incredibly augmented strength, displaying that Koji is much stronger than he looks.
Koji has been shown to use the quirk effectively with flocks of birds to create a smokescreen of animals and to attack an opponent along with his use of insects to distract and attack his opponents. He has now also overcome his fear of bugs, so he often uses bugs to swarm an opponent with numbers.
As part of his training, Koji engaged in vocal exercises to increase the range of his Anivoice, allowing him to control animals from long distances.
Battles & Events
|Battles & Events|
- According to Koji's profile in Volume 5:
- His favorite thing is nature.
- Kohei Horikoshi likes his non-human design.
- Koji's known U.A. data is as follows:
- Koji and Rikido Sato are currently the only students in Class 1-A without a named Super Move.
- Koji's surname contains the kanji for "mouth" (口 kō?) and "rice field" (田 da?), and his first name contains "shell, armor" or "high voice" (甲 kō?), and "boss, to rule" (司 ji?).
- Koji's first line of dialogue happened in Chapter 66, 61 chapters after his debut.
- With his birthday taking place in February, Koji is the third youngest student in Class 1-A, as everyone was 15 when they started U.A.'s school year in early April.
- For unknown reasons, Koji has inconsistent skin color in manga artwork, usually changing between peach, coral and even gold.
- Koji's horn apparently grows with age, and is still not fully matured yet.
- Koji is the only student in Class 1-A confirmed to have a pet; a rabbit named "Yuwai-chan", also dubbed "Kawaii-chan" by Koji's female classmates.
- (To himself) "That's right. I got into U.A. High, my dream school... At U.A., it's always about moving forward! That's what we tell ourselves... Plus Ultra!!"