Hayro Rich, also known as Hairo Rich, is a character introduced in the second major story arc of the manga and anime. He is a young man who first appears as a soldier serving the Bennett Church Army before becoming a member of the immortal army assembled to fight alongside the protagonist, Fushi. He is approximately eighteen years old at the time of his introduction, with a later time skip showing him at twenty-two.

Hayro's past is marked by a traumatic childhood spent under the authority of the Bennett Church. He was brought to the church as a child because others believed a demon possessed him. His earliest memory consists of having all his teeth repeatedly pulled out every time a new one grew, forcing him to subsist on a diet of runny soup and porridge. He was raised by a foster mother named Mother Tasette, who was caring and cautious. On one birthday, she gifted him prosthetic teeth, an act that dramatically changed his world for the better. Tragically, she was replaced the very next day for having committed a sin, an event that hints at the harsh and unforgiving nature of the church.

The most defining aspect of Hayro’s character is his unique physical condition: he is unable to feel physical pain, a trait he has possessed since birth. While he can feel temperature and touch, pain signals do not register in his body. This immunity to pain makes him a remarkably stable and reliable fighter, as he does not flinch or become incapacitated by injuries. However, this trait is also a significant weakness. Because he cannot feel his own wounds, he may fail to notice when he is seriously hurt. More profoundly, his inability to experience pain creates a barrier to understanding the emotional suffering of others, as pain is a fundamental part of the human experience that fosters empathy. The only form of pain he can truly experience is mental or emotional anguish, a distinction noted by Fushi when he transforms into Hayro.

Despite his painful upbringing, Hayro aspired to become a swordsman after learning about them in a book. He achieved this goal, rising to become the head soldier of the Bennett Church army through his accrued experience and dedicated training, making him a highly skilled combatant. His motivation to leave the church and join Bonchien Nicoli La Tasty Peach Uralis, or Bon, stemmed from a desire to escape. He decided that if a chance to flee ever presented itself, he would take it, and Bon ultimately found him and recruited him for Fushi’s cause.

Within the narrative, Hayro’s role is that of a valuable ally in the battle against the Nokkers. He is one of three warriors, alongside Kai Renald Rawle and Messar Robin Bastar, whom Bon selects to be new vessels for Fushi, believing in their loyalty, apostasy, and cunning. These three willingly offer themselves to fight, understanding the immense risk. During the fierce battle to defend the city of Renril, Hayro, Kai, and Messar all fall in combat. However, they are later resurrected, becoming part of the growing number of individuals brought back to continue the fight and live on in a world at peace, eventually joining Fushi and his other resurrected friends in their final moments of shared reflection.