|Abele Altoromagi (father, deceased)|
Kirino has long black hair in which she takes great pride and hazel eyes; and is usually seen wearing her school uniform.
Kirino doesn't like being imprisoned all day in her school, so she takes walks secretly and is later scolded for breaking the rules. She also seems to have an interest in photography.
Kirino's father is Abele Altoromagi, an Italian human rights lawyer, her mother is a Japanese woman. At the age of five or six she meets the fourteen-year-old Toma after he is found by the charity organization headed by her father. Reminding him of his late sister, Toma asks her to be his new princess.
Eventually, Kirino meets Sasayama and Kogami in Ogishima. Later when she and Sasayama find her father's corpse, Toma remembers the now teenaged girl as the one he once asked to be his replacement princess after he murders his real life sister, Princess. He pursues her, but Sasayama saves her, telling her to go to the MWPSB, which she does.
Kirino escapes but is found by Makishima and his subordinates who give her an injection. She is later found by the MWPSB with brain damage, unable to communicate and the entire case is foiled without a witness.
Because Kirino reminds him of his deceased sister, Mari Sasayama, Sasayama feels overly protective towards her which results in him having to withdraw from the case. And when Toma attempts to capture Kirino, Sasayama saves her.
However, Kirino doesn't like Sasayama's rude attitude due to the fact that nobody has ever been impolite to her before.
Kirino has a crush on him because she has a dream of him asking her to be his princess which is, in fact, just a long-forgotten memory. Toma, who has asked her to be his new princess years ago, even kills her father because he fears that he could separate him from his deceased sister's corpse, which he keeps in a refrigerator in their childhood home.
- After marriage and becoming a Japanese citizen, Altoromagi changes his surname to Kirino ‒ the surname of his wife, which their daughter also uses.