Short Answer: Although he wasn’t born as one like Zero Two, Hiro became a Klaxo Sapien later in the show. This was because when Hiro ingested the Klaxo Sapien Blood of Zero Two, his genes were altered and his transformation was escalated due to Hiro consistently piloting a Franxx with Zero Two. This caused the mutation process to speed up and eventually Hiro gets completely transformed into a Klaxo Sapien.
Darling in the Franxx has portrayed the transformation of Hiro from a normal human to a full-fledged KlaxoSapien in an intriguing way, causing fans to wonder about the events that contribute to the overall transformation of Hiro. Let’s get into the backstory of Klaxosaurs and how Hiro inherited their blood while transforming into a KlaxoSapien himself.
What are Klaxosaurs?
Darling in the Franxx features biomechanical creatures called Klaxosaurs that first appeared when the APE organization extracted magma energy from the earth’s core. At first, they seem to be wild creatures without any consciousness, but later we discover that Klaxosaurs are the weapons that came into being when an ancient race known as Klaxo Sapiens sacrificed their bodies to protect their planet from an extraterrestrial race called VIRM. The Klaxo Sapiens divided themselves into pairs; males became the core while females became the body of beings called Klaxosaur.
“We believed that by abandoning our ties and embracing solitude, we could perfect ourselves, make ourselves stronger.”
Code 001 to Hiro and Zero Two
The Klaxosaurs are classified into four groups: Conrad, Mohorovicic, Gutenberg, and Super Lehmann. Conrad is the weakest class of Klaxosaurs that are easy to defeat, while Super Lehmann is the strongest class of Klaxosaurs as they are about the size of a giant plantation, making them a very serious threat. All Klaxo Sapiens, with the exception of Klaxosaur Princess (001), are extinct in the current timeline of Darling in the Franxx, as they evolved into Klaxosaurs and Magma Energy centuries ago.
There are several more interesting facts about Darling in the Franxx that you might have missed, but you can check them out by clicking here to read our article “Top 10 Things You Might Not Know About Darling in the Franxx.”
Is Zero Two a Klaxosaur?
People mistake Zero Two for a Klaxosaur, but in reality, she is a Human-KlaxoSapien Hybrid as Dr. Franxx created her from the hair strands of Klaxosaur Princess, also known as Code 001. The continuous extraction of Magma Energy and Dr. Franxx’s research about Klaxosasurs eventually led him to Klaxosaur Princess, who turned out to be the last survivor of an ancient race called Klaxo Sapiens. Upon discovering the cruel deeds of Dr. Franxx, she devoured one of his arms but let him go as she deemed his sins far too grave to be punished with mere death, unaware that he had taken some of her hair strands, as shown in episode 19 of Darling in the Franxx.
“It was like I was put under a spell. Her two alluring horns, and my first ever look at a naked girl’s body, left me transfixed, unable to take my eyes off of her.”
Hiro to himself, upon his first meeting with Zero Two
Later, Dr. Franxx extracted the KlaxoSapien DNA from her hair strands and began to perform several experiments, hoping to create a clone of the KlaxoSapien Princess. After several failed attempts, he managed to create a clone that inherited the KlaxoSapien Blood and gave her the codename 002, later known as Zero Two. It is worth noting that Zero Two didn’t inherit the supernatural powers of Klaxosaur Princess, like Telepathy and Retractable Spider Appendages, cause she is an artificial clone and some genetic mutations are quite normal in this case.
How it all began
In childhood, Hiro was quite different from other children in terms of personality and aptitude. Despite being born as an artificial human without any parents, Hiro showed characteristics of a normal child, unlike other emotionless children. Moreover, Hiro had a great aptitude for compatibility tests and experiments regarding Franxx; that’s why adults gave him special treatment.
“Sure, Hiro was special. Even among the double-digits, he was a cut above. We were all certain that he’d be our leader and show us the way. But reality had other ideas. Hiro couldn’t become a parasite. He’s not who he used to be. We must give up and cut our losses. I don’t want to see this pathetic side of Hiro anymore.”
Mitsuru talking about change in Hiro to Ichigo
However, a certain incident changed his life as he witnessed a girl with red skin and horns getting tortured by adults. Unable to let this pass, Hiro decided to make an escape from this facility along with the girl. Hiro named her Zero Two during the journey and developed a strong bond with her. As they venture through the blizzard, Zero Two sustains an injury on her leg resulting in blue blood sprouting out, much to Hiro’s surprise. He ended up licking her wound to heal it while ingesting her Klaxo Sapien Blood. Eventually, the Klaxo Sapien Blood altered his genetics, causing Hiro to lose his aptitude for piloting Franxx. The adults deemed him useless as he could no longer become a parasite, but Dr. Franxx kept him alive as he was intrigued by this genetic development, as shown in episode 13 of Darling in the Franxx.
Signs that Hiro was changing
Hiro lost his piloting ability right after ingesting the Klaxo Sapien Blood of Zero Two as the number of yellow blood cells in his body increased to the point no pistil could maintain the piloting connection with him. However, this was just the first effect of the Klaxo Sapien Blood. Later, Hiro became Zero Two’s partner and managed to pilot Franxx again but piloting Franxx with a Human-Klaxo Sapien Hybrid, like Zero Two, awakened the ingested blood, causing Hiro to develop a Blue Tumor on his chest. Hiro’s physical condition continued to deteriorate with each successive ride with Zero Two. Eventually, Hiro falls unconscious during the third ride, but upon watching Zero Two suffering alone, he takes a leap of faith, and with willpower, Hiro manages to reverse the effects of the tumor. Afterward, Hiro’s compatibility with Zero Two continues to increase, indicating the genetic mutation in Hiro.
“You are such a complete, utter fool!”
Goro to Hiro about Hiro choosing to keep riding with Zero Two
Nana and Hachi predicted that Hiro would soon go through a process called Saurification that happens in Parasites due to an increase in Yellow Blood Cells. Since Hiro had ingested Zero Two’s blood, his Yellow Blood Cells have increased beyond critical levels, causing him to develop canines and horns like Zero Two.
What is Hiro?
After going through the events mentioned above, Hiro transcended from being a normal human to another being close to Klaxosaurs. After retrieving control of Star Entity from VIRM, Hiro and Zero Two destroyed their army, but that was just their front fleet as their main army lies in another dimension. Zero Two consciousness remained merged with Star Entity and left earth to pursue VIRM. Upon realizing this tragedy, Hiro went to space and decided to merge with Star Entity so that he could be together with his beloved Zero Two. Star Entity merged itself with Hiro and eventually transformed him into a full-fledged Hybrid Klaxo Sapien just like Zero Two, as shown in episode 24 of Darling in the Franxx.
“Zero Two…we’re becoming one. Now you are me… We’re probably going to disappear soon but the path we walked on, others will take it from here… I love you, Zero two”
Hiro’s last words, to Zero Two before his death
Hiro gained blue horns and blue skin color after transforming into Hybrid KlaxoSapien, while Zero Two had red horns and red skin color. Ideally, Hiro should have the same characteristics as Zero Two cause he ingested KlaxoSapien Blood from her. On the other hand, since Zero Two also didn’t gain all characteristics of Klaxosaur Princess and Hiro most likely gained different horns and skin color probably because of genetic mutations.
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Papa and his organization APE seemed shady right from the beginning of Darling in the Franxx and countless things about them remain unclear even after watching the entire series, which is quite frustrating for fans.
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Darling in the Franxx left an everlasting impression on the audience, causing them to wonder how interesting and entertaining it would be for Darling in the Franxx to have a Season 2. The events featured in the finale, like VIRM’s claim about their inevitable return, are one of the intriguing things to look forward to in Season 2. Considering the success of Darling in the Franxx Season 1 and some elements left in the finale, it is possible for Darling in the Franxx to return with a Season 2.
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Our Final Thoughts:
In the end, Hiro’s encounter with Zero Two changed his whole life, and even though Hiro had to go through various troublesome situations, he doesn’t regret meeting Zero Two as he loves her to the point he doesn’t mind becoming a Klaxosaur or whatever to be together with her. Zero Two deemed her story as the story featured in her treasured picture book where the heroine is a monster and ends up leaving the prince to protect him, but fortunately, Zero Two’s story didn’t end the same way as Hiro became a Hybrid KlaxoSapien just for staying together with her till eternity.
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