Hiro

As a child, Hiro was very jovial, optimistic, and hopeful, giving names to other kids and to himself as well. He taught the kids that names only given to themselves could give a sense of uniqueness when the only name they had was their codes. This earned him fame among other children, even those in other plantations. Because of this, he was chosen to represent the Children in the Garden. During his time at the Garden, Hiro was very curious about himself and the world around him. He would constantly ask himself questions and whenever he tried to ask the adults, they would never give him an answer. This, coupled with the fact that the other Children never took a stand with him and were very obedient, made Hiro frustrated and he felt like he was the only person fighting the world all by himself. This changed when he met Zero Two, to which Hiro realized that there were other people fighting the world by themselves. He was then shown to be tenacious and brave, as he didn't bother to wait to rescue Zero Two and broke her out of her room and helped her evade the authorities for a while all by himself. However, after getting caught, the authorities decided to erase both of their memories: Hiro's curiosity, free-spirited nature, and meeting with Zero Two were few of the reasons why. After this, Hiro became less curious, joyful and creative, and more emphatic, serious and obedient. He also stopped naming children and was stripped off of some of the original aspects of his personality. Prior of his memory wipe, Hiro only wanted to pilot in as much as it would let him leave the Garden, but when this motivation was erased from his memory, piloting was all he remembered and his sole purpose for living. Because he was considered a role model, all of the children hoped he would lead them because he was the best pilot, but Hiro's aptitude skill began to dip after he ingested a young Zero Two's blood. This inability to pilot a FRANXX had left his hopes low, even to the point of choosing to leave the Thirteenth Plantation until his former partner Naomi encouraged him to stay. Losing the ability to pilot had left him with extremely low self-confidence and left a insecure feeling that his life had little worth. He initially struggled to find somewhere to belong, even to the extent that he was more than willing to ride with Zero Two even if it meant death. Part of the reason why he was determined to keep on piloting Strelizia is because he was finally able to fulfill his role as a Parasite, and he was willing to die fighting than live as a useless civilian. However, this wish of his came to an end after he survived his third ride with Zero Two. It was then he realized that he had found another reason to fight beside protecting Papa and the adults: to become Zero Two's wings. Hiro appears to be quite philosophical, as he was first introduced as him monologuing about the philosophical meaning of a wounded bird he saw in the forest, indicating that he still had retained the curiosity of the outside world from his childhood. In his time in the Garden, he spent his time teaching Ichigo and Goro about many old but meaningful sayings that would stick to them even as they grew up. Hiro was shown to be very hardworking and devoted, as he refused to stop piloting with Zero Two and when he trained in a FRANXX training unit all day and all night so he could be useful and fight alongside the other Parasites. He was also kind and caring, as despite feeling depressed over his inability to pilot, he never acted in a harsh manner towards his fellow pilots, even when some of them weren't as welcoming towards him. However, he was more than willing to fight back when Zorome antagonized him several times. He was determined to prove himself worthy to pilot and make himself acknowledged. When he got promoted to an official Parasite, he states that he would do his best and not tie them down. After regaining his memories, Hiro regains his former personality. Also, thanks to Zero Two's influence and his bonds with people, he understood that there were more to life than just to pilot a FRANXX. He also began thinking about the future and all the possible paths that were open for all of them. He teaches all of this to his friends in Squad 13. Instead of the "fight until I die" mentality, Hiro developed a "fight so I can keep living" mentality. His traits from childhood also started to resurface: he became fearless, disobedient, rebellious and ready to stand up for his friends, even it meant going against the rules. This is seen where when Papa and the others destroyed Squad 13's happy and peaceful life, especially in regard to Mitsuru and Kokoro's memories being erased due to their decision to get married, Hiro told Papa that he would never see him as their ‘papa’ nor obey him ever again after what he did to his two friends, insisting that the Parasites would be free from APE after their final battle. He became increasingly adamant about gaining freedom ...

Hiro had an average build, height, and a standard "slim" male physique. He had black, straight hair, in a razored haircut, and rich blue eyes. His checkered past had left him with an emphatic expression on his face. He was often seen in the standard Stamen uniform which consists of a white collared top with formal long grey sleeves and a matching grey midsection, while the chest area is colored navy blue with the respective Parasites cadet badge pinned on the left side, which is separated with an upside-down Y shaped pin-like embellishment on the center which is exclusive for male Parasites only, on the back of the uniform a white pinstriped diamond-shaped patch is seen between the shoulder blades. The uniform is paired with light-grey mid-length high-waisted shorts stopping just above the knees which has symmetrical two black buttons on the stomach area, and dark garter socks held by a pair of black straps around the calf, brown shoes and ankle-length black socks which seems to wrap around the shoes by the corner. thumb|left|Hiro's tumor which emerged after his second time piloting with Zero Two. Starting from Episode 05, he had a blue tumor-like mutation in his chest, caused by piloting with Zero Two, which increased his yellow blood cell count, the polar opposite of what happened when Zero Two rode with other parasites. This mutation later grew larger due to piloting with Zero Two again, however Hiro was able to overcome the mutation using his willpower, and completely got rid of it, although a scar was left on his chest. Hiro's appearance after his fully completed saurification. Starting from Episode 17, Hiro developed canines and he also began sprouting small blue horns due to his "saurification". His horns eventually began to lengthen significantly and glow blue, the same way Zero Two's do when emotionally agitated. His eyes become luminescent, changing from a dark blue-green to bright blue. His irises also gained more blue hues and rings, and he also developed a blue eyeliner similar to Zero Two's. His fangs grew out when he was enraged. Right before his demise, Hiro was shown to have blue skin, similar to that of the klaxo-sapiens.