Shizuku's beloved brother. Shizuku loves Ikki dearly as a child and was saddened when Ikki left the house and was shocked to see that her family didn't even show a hint of care. Following that incident, Shizuku decides to love him in the place of her parents, siblings, friends and lover.
Shizuku and Stella are on extremely bad terms with each other, mainly due to the two of them being after the same man. Shizuku views Stella as an eyesore for loving and trying to take Ikki away from her, while Stella considers Shizuku a sick and dangerous sister who loves her brother incestuously.
Although these feelings of hate begin to change into feelings of respect and admiration, after the events of Rebellion's first attack, where she sees Stella was willing to be humiliated all for the sake of some random people, and was still able to beat the goons after being humiliated.
Shizuku's roommate. Arisu is the only person Shizuku has open to aside from Ikki despite her misanthropy resulting from Ikki leaving the house. Nagi seems to also understand Shizuku on a very deep and emotional level, as he was the only one who was able to comfort Shizuku, when she had lost her match with Tohka.
Shizuku and Nagi relationship had grown to a point to where they see each other as sisters. Shizuku was even willing to risk her own life against an opponent she could not possibly beat all to save Nagi who had just admitted to being a traitor to Hagun Academy.
Shizuku doesn't like her own father, as he had been the cause of Ikki's disappearance. The regret in Shizuku's heart, of not knowing how Itsuki and the rest of the family treated Ikki, turned into anger at Iwao, who could not find any love for his F ranked son.
Shizuku apparently loves her mother, returning home after receiving a letter from her. Thus she came to hate her father more as he execrably took advantage of Shizuku's positive relationship, with her mother, as Itsuki made his wife to write the letter so that he can see his daughter.
Her eldest brother. He has abandoned their family, thus no longer considers them as important.
Shizuku admires Kiriko, who is one of the most skillful water users in the world, even better than Shizuku. Shizuku holds her in a high regard, even asking Kiriko to train her.