Mitty is an amorphous Narehate, also referred to as a Hollow, who resided with Nanachi on the fourth layer of the Abyss. She was originally a human girl before being subjected to the curse of the sixth layer during forced ascent from Bondrewd’s experiments. This transformation twisted her body into a monstrous, blob-like form with patches of fur and a misshapen face that retained a pair of expressive eyes. Her mind deteriorated significantly, leaving her unable to speak or communicate in any conventional way, though she could emit cries and growls. Despite this, she retained some level of awareness and recognition, particularly of Nanachi. Her soul was effectively imprisoned within her altered body.

Before her transformation, Mitty was a cheerful, kindhearted, and optimistic girl who admired the Abyss. When she and Nanachi were held captive by Bondrewd, they became close friends. After the experiment, Nanachi escaped with Mitty and cared for her in isolation on the fourth layer. Mitty’s existence was defined by her bond with Nanachi, who was her primary motivation and source of comfort. She showed signs of fondness and attempted to comfort others, such as when she carefully hugged the unconscious Riko. Her motivations were not complex but centered on companionship and the emotional connection she maintained with Nanachi.

Mitty’s role in the story is that of a tragic victim whose suffering and relationship with Nanachi form the emotional core of the series’ first season. She serves as a catalyst for Nanachi’s character arc, which revolves around guilt, love, and the desire for release. Her most significant relationship is with Nanachi, who considers her their most precious treasure. The bond between them is forged through shared trauma and unwavering devotion. Nanachi’s decision to ask Reg to use his Incinerator to destroy Mitty, because it can erase the rules of the Abyss and truly kill her, is a pivotal moment. This act frees Mitty from immortal suffering and allows Nanachi to move forward. Later, in the Village of Iruburu, a perfect replica of Mitty is created by Belaf, which retains a copy of her soul from the moment of her death. This replica serves as a source of value for Belaf and a haunting reminder of the original.

Mitty’s most notable ability is her immortality. In her Narehate form, she can regenerate from any wound, no matter how severe, and is immune to conventional death. She can also neutralize poisons, though this process is painful and takes time. This immortality was exploited by Bondrewd for further experimentation. The only known method to permanently kill her is the Incinerator, which rewrites the Abyss’s rules. Some sources suggest she has a degree of shapeshifting, but her defining physical trait is her amorphous, regenerative body. Her development is primarily about her tragic transformation and eventual release, with her replica continuing her legacy in a different form. Overall, Mitty represents the harsh consequences of the Abyss’s depths and the enduring power of love and friendship even in the face of unimaginable suffering.