Saeko

was the wife of the Kawaguchi Metal Fittings Corporation's manager. She was infected by the Human Body Ignition Phenomenon, turning her into a Flame Human.

Appearance
As a Flame Human, Saeko had fiery flowing hair, and black charcoal-like skin with the rest of her body being enveloped in flames, no mouth and solid-colored eyes with black sclera.

Personality
While a Flame Human, Saeko was peculiarly intelligent. As usual to Flame Humans, she was driven by rampage and chaos, and burned everything in sight. She was protective of the Kawaguchi Metal Fittings Corporation, quite possibly due to her husband's affiliation with the factory. In battle, she was very cautious of her surroundings.

Plot
Saeko turns into a First Generation and begins rampaging in her husband's factory, forcing the 8th Special Fire Brigade to arrive at the scene. Sneaking up behind Shinra, she absorbs the flames around her and strikes the boy, blowing him away and leaving him unconscious. As Shinra regains awareness, Saeko begins emerging towards the brigade, noticeably more adept in battle and quick on her feet compared to the other Flame Human that Shinra witnessed at the train station. She is stopped by Akitaru, with Maki blasting away the flames to prevent Akitaru from getting burned. The Battalion Commander then used his weapon attack, aiming to impale her core, but Saeko counterattacks and hits the weapon out of Akitaru's hand, forcing the brigade to separate to safety. As Shinra recalls his past and remembers his promise to his mother, he charges towards Saeko with a blazing kick, successfully impaling her core and sending the woman's soul off into the "raging flames". When the brigade left the factory, Saeko's husband. who was waiting outside, bursts into tears while thanking Shinra that they were able to send her off peacefully.