Mother (Natsuko), Father, Older sister (Nao) and younger sister (Nami).
Komatsu came to Tokyo, looking to find her dream. Unlike Osaki, Komatsu came from a large and happy household, though her childish outlook prevented her from living on her own initially. She's the middle child of three sisters.
Her chance encounter with Osaki began a friendship which changes Komatsu's life forever. She is introduced to Osaki's band, Black Stones, and their members. She later even helps "Blast" to find their bassist, by drawing a poster to advertise the vacancy. Much to her surprise, she also discovers that the members of Blast were friends with the members of Trapnest, a popular rock band of which she's a very big fan.
Trivia: Her nickname "Hachi/Hachiko" is a play on words for both the Japanese No.8, as well as a reference to the loyal dog "Hachi," who waited 9 years following his owner's death. The nickname fits very well as Nana "Hachi" is seen as Nana No.2 (Nana means No.7, depending on the Kanji), and is known to be very depending on others and blindly loyal (at least in the beginning of the series).
(Source: Wikia)
