Yuu

Yuu is kind, responsible and unusually brave for a child who lives among adults regularly exposed to deadly combustion incidents. He responds strongly to acts of heroism and remembers people who help him.

He is passionate about machines and wants to learn from Vulcan Joseph. Because Haijima's pressure makes it difficult for Vulcan to obtain supplies, Yuu searches for usable components himself and carries them back to the workshop.

Yuu is also deeply attached to the makeshift family he forms with Vulcan and Lisa Isaribi. Their workshop is his home as well as the place where he learns his trade.

Yuu is not established as a pyrokinetic and has no demonstrated Ignition Ability. His developing talents lie in mechanics, scavenging and assisting Vulcan with engineering work.

He understands enough about the workshop to locate useful materials and help with Vulcan's projects. His practical experience grows from working directly beside one of the series' most accomplished engineers.

Yuu's other notable quality is courage. Early in the story, he attempts to defend Shinra Kusakabe verbally when Company 5 surrounds the Fire Soldier, despite having no combat power with which to challenge them.

Yuu first encounters Shinra during the incident involving Setsuo Miyamoto. Shinra protects him from the Infernal, and Yuu subsequently tries to intervene when Company 5 treats Shinra as an enemy.

He reappears at Vulcan's workshop and recognizes Shinra when Company 8 arrives seeking the engineer. Unlike Vulcan, Yuu is willing to hear the visitors out and brings Shinra, Arthur Boyle and Iris inside.

During the attack on the workshop, Yuu becomes one of the civilians caught in the struggle over Vulcan's family legacy. Giovanni seriously injures him to force Vulcan to surrender information about the Key to Amaterasu.

Much later, Giovanni implants a parasitic insect into Yuu and uses it to seize control of his body during the Cataclysm. Arthur ultimately removes the parasite without destroying Yuu's brain, freeing him from Giovanni's control.

Vulcan Joseph is Yuu's mentor and the person he considers his master despite Vulcan's objections to the title. Yuu admires his engineering and shares the workshop with him.

Lisa Isaribi is another member of Yuu's makeshift family. Her initial betrayal shocks him, but their genuine familial attachment survives the revelation of her White-Clad mission.

Shinra Kusakabe saves Yuu from Setsuo Miyamoto, earning the boy's gratitude and reinforcing his belief that Shinra behaves like a genuine hero.

Dr. Giovanni targets Yuu because of his relationship with Vulcan. Giovanni first seriously injures him as leverage and later uses a parasite to take control of his body.

Arthur Boyle becomes one of Yuu's allies through Company 8 and eventually frees him from Giovanni's parasitic control.

Iris meets Yuu at Vulcan's workshop and helps care for him after Giovanni's attack.