Mitty/Relationships

Belafu
Belafu offered up most of his body in order to create a perfect copy of Mitty, which even contains her soul, in Ilblu. After doing so he mainly used her as source of food, due to her ability, but stopped doing so after Nanachi offered themself to Belafu in exchange for the copy of Mitty.

Bondrewd
When Mitty first met Bondrewd, she looked up to him and wanted to become a White Whistle herself. When Bondrewd revealed to her and Nanachi that he was going to use them as test subjects she was shocked. After becomming a cursed Narehate, Bondrewd continued testing the limits to Mitty's acquired immortality until Nanachi escaped with her.

Nanachi
Mitty was the only one of the other children to approach Nanachi, the others complaining that they smelled bad. Mitty was impressed with Nanachi's artistic skills and knowledge, and asked to pair up. Nanachi was reluctant at first, but Mitty insisted, and her gentle enthusiasm quickly won Nanachi over. The two grew very close, and were practically inseparable. One possible interpretation is that Nanachi may have even had romantic feelings towards Mitty, as Nanachi would blush at Mitty's compliments or when they were in close quarters, and would draw pictures of her absentmindedly. The two often held hands, hugged, slept side by side, and were generally very intimate with one another.

During Bondrewd's experiment, just before the two ascended from the 6th layer, Mitty's last words were a tearful proclamation that she wished for her soul to accompany Nanachi if she did not survive. Mitty did survive, but was left in a permanently unrecognizable state — transformed forever into a Narehate, and cursed with immortality. After seeing Bondrewd's relentless torture of Mitty's new Narehate form, Nanachi escaped Idofront with Mitty and vowed to free Mitty's soul from her current physical state. Until that day, their hideout in the 4th layer was filled with all sorts of books, homemade plushies, and pillows and blankets, all with the goal of enriching Mitty's life. Nanachi treated her as if she was still a self-aware being, and would talk and read books to her. Despite their peaceful living, Nanachi felt that Mitty was their only reason to be alive, and had planned to take their own life after her death was accomplished. Nanachi felt very strongly about this mindset, going so far as to call Reg cruel when he made them promise not to.

When the day came, Nanachi set up a large nest full of pillows and other items they had made for Mitty, so that she could be in comfort even as she was being released. Nanachi said their goodbyes, telling Mitty they would meet again. Only a minute later they recanted this, saying instead they would always be together. When the deed was done, Nanachi fell to their knees and cried intensely, proclaiming Mitty to be their "treasure".

Nanachi copes with their loss by telling themself that they will one day meet Mitty again, though they stated that they don't really believe this will happen. Even so, Nanachi holds onto hope with belief that everything returns to the Abyss, and has even been preparing for their fated meeting by learning how to cook good food.