Nono Kurusu is a third-year high school student at Hekiho Academy and the vice president of the school's newspaper club. She lost her parents in the Great Shibuya Earthquake and later came to live at the Aoba Dorm, an orphanage and foster home, alongside Takuru Miyashiro, whom she regards as a foster younger brother. She is a gentle and caring person who is well liked at school, earning the nickname Empress for her mature and composed demeanor despite being a teenager. Her primary motivation is to protect Takuru and encourage him to pursue a stable future, such as attending college, because she wants him to avoid danger after the trauma of the earthquake.

In the story, Nono initially opposes Takuru's involvement in the Return of the New Generation Madness murder investigations, fearing for his safety and believing that reopening old wounds will only cause more harm. However, a major revelation changes everything: the real Nono Kurusu died in the Great Shibuya Earthquake. The person living as Nono is actually Senri Minamisawa, a childhood friend of the real Nono who survived the disaster and assumed Nono's identity. Senri, using Nono's name and appearance, became Takuru's foster sister and lived alongside him, though she carried the guilt of this deception. This dual identity means that the character presented as Nono throughout most of the series is actually Senri, who possesses the ability to sense others' emotions and has a depth of understanding shaped by her own traumatic past.

As Senri under the Nono persona, she acts as a stabilizing force in Takuru's life, often shouldering responsibility and trying to steer him away from the dangerous truths surrounding the murders. Her relationship with Takuru evolves from that of a protective older sister to someone who must confront the weight of her lie and its effect on him. Notable traits include her strong sense of duty, her ability to remain calm under pressure, and her deep emotional awareness of those around her. Despite lacking any supernatural powers herself, her perceptive nature and genuine care for others make her an important figure in the narrative, both as a foil to Takuru's recklessness and as a key to understanding the truth of the earthquake's aftermath. Her character development involves facing the consequences of her assumed identity and ultimately finding a way to support Takuru while reconciling her past.