Nanami Shiranui is the youngest of the three protagonists and a member of the crew aboard the airship Norn. She has a doll-like appearance, with short, unkempt light purple hair, purple eyes, and a mole beneath her left eye. Her quiet and reserved demeanor makes her easy to overlook, and few people on the ship notice her presence unless she chooses to be seen. She is polite and naive, but her initial emotionless expression hides a more complex interior.

Nanami descends from the Shiranui ninja clan and was raised as a kunoichi. She possesses excellent physical abilities, remarkable agility, and skill with ninja weapons, particularly kunai. Her clan's true power, however, is the ability to erase specific memories from other people. This ability is the central conflict of her character. She deeply hates her own power because of the pain it causes both herself and others, and she tries to keep others at a distance to avoid having to make them forget her or anything involving her. Her dark past is tied closely to this power and to her role within the Shiranui clan.

Despite her fragile appearance, Nanami is a capable fighter and a dangerous opponent when the situation demands it. Her personality is characterized by reticence and a sense of being an oddball with a different perspective from those around her. At the same time, she is sensitive to the feelings of others and able to read the emotional atmosphere. She maintains good relationships with Heishi Otomaru and Itsuki Kagami among the male members of the crew.

Nanami's role in the story is heavily shaped by her trauma and her wish to avoid harming others with her memory-erasing ability. Over the course of the narrative, she must confront her past and the burden of her power, gradually learning to trust the people around her and open up emotionally. Her development centers on reconciling her identity as a ninja of the Shiranui clan with her own desires and her place among the other gifted individuals on the Norn.