Akasaka is a young man who serves as the protagonist of the Mold segment in the sixth episode of the series. His background reveals that he had been living abroad for a year due to work commitments, having purchased a house that was left empty during his overseas project. Before his departure, he was pressured by his high school teacher, Shimao Rogi, and Rogis family to rent them the house, as they had lost their own home in a fire and claimed to have nowhere else to live. Akasakas brother, Seiji, facilitated this arrangement, and Akasaka only agreed to the rental on the condition that the family would take care of his dog while he was away.

In terms of personality, Akasaka is portrayed as someone with reasonable expectations for the care of his property, and his reactions to finding his home in a state of ruin are driven by frustration and a sense of violation. Upon returning from his work abroad, he discovers his house in a shockingly filthy condition, with mold growing everywhere, a trashed living room, and a refrigerator containing rotten, foul-smelling food. His fury is directed primarily at his brother Seiji, whom he holds responsible for the state of his home, and he also suspects that his former teacher Rogi might have harbored a grudge against him, possibly stemming from an incident in high school where Akasaka allegedly destroyed a shelf containing Rogis specimens. His motivations throughout the story are practical and grounded in a desire for accountability. He seeks to locate the missing Rogi family to hold them responsible for the destruction, and he also asks his brother if he can stay with him as his own house becomes increasingly uninhabitable.

Akasakas key relationship in the story is with his brother, Seiji. Seiji is a problematic figure who pressures Akasaka into renting the house, assumes responsibility for the mess but quickly exits, and ultimately refuses to help his brother when he is most in need. Seiji recalls seeing that the Rogi familys children were covered in mold and had developed flaky skin when he visited them earlier, and he notices that Akasaka himself has become infested with the fungus. Rather than offering aid, Seiji abandons Akasaka to his fate, leaving him to perish in the mold-infested house.

The development of Akasakas character is one of gradual physical and psychological deterioration. As the mold spreads through his home, it also begins to affect him directly. He wakes to find his house in an even worse state than before, discovers a locked room that has been destroyed by the mold, and inside finds the decayed, decomposed bodies of the Rogi family, who had become a breeding ground for the fungus. The story concludes with Akasaka idly scratching at himself, muttering the word itchy as his condition worsens. He has no special abilities, and his fate is sealed by the supernatural or biological horror of the mold that consumes his environment and his body.