Chiyo Aiba

is the sister of Izō Aiba.

Appearance
Chiyo is a young girl with dark hair worn in pigtails. She wears a light-colored sleeve over a black undershirt and vertically striped shorts.

Personality
Chiyo is a precocious girl, that is quite developed in terms of speech and intellect despite her apparent young age. In addition, she appears to favor things in the romantic sense as she follows the advice of her love fortune; upon sight, she has fallen in love with Beel.

She also holds a strong belief over fortunes as after reading one about a wonderful encounter on a southern island, she decides to accompany her brother to his class trip.

Okinawa Arc
Chiyo is initially seen asleep on Izō Aiba's back as he deals with the delinquents in his school who had provoked a fight with Ishiyama High.

She remains silent and subdued until Izō and she encounter Oga and Beel in the hallway. Chiyo then takes notices of Beel and blushes, in which her brother explains that she has fallen in love with Beel.

Later, they are shown in Aoi Kunieda's room where Chiyo introduces herself to Beel. Izō questions what she likes about him, and she refuses to answer as it is inappropriate. She then blushes when her brother refers to her spending time with Beel as a date.

Subsequently, Aoi asks Chiyo why she has decided to go on the class trip with Izō. The latter explains that she likes reading fortune-telling books. She has read one that foretold her she would encounter something wonderful on a southern island. She rummages through her bag and hands over a magazine that discusses zodiac signs and love fortunes. Chiyo asserts that she and her brother are Virgos, and that her love points are ninety-five. In other words, it is interpreted as take some action in terms of romance. Aoi says that she is a Taurus, and Chiyo claims that she has a great capability with Virgos.

When she and Beel are playing together, she meets Futaba and both of them end up fighting for Beel. When they ask Beel who he loves, Beel, scared, runs back to Oga. This forces them to postpone their battle as they claim Beel still loves his father, Oga, the most.