Chiu (ちう) is a famous Net Idol and the secret alter-ego of Chisame Hasegawa, who uses her cosplay and computer skills to further Chiu's career on the internet as a glamour model and blog writer.
Chiu's popularity is such that her site is regarded as one of the most visited websites in Japan and as such she has a big fanbase.
While she has tried to keep her alter-ego a secret from her class-mates, Chisame was unable to keep it from Negi Springfield. Other classmates also learn her identity soon after, such as Kazumi Asakura who used an image of her in a cosplay as Chiu as blackmail to help the class in the anime.
- As a Net Idol, Chiu has her own website; Chiu's Net Idol Information, which was momentarily in competition with a website created by Class 2-A in the anime.
- Chisame's image on her Pactio card is of herself dressed up as Chiu.
- During the Mahora Academy School Festival's second day, Chisame was given an age regressing pill by Chachamaru and regressed to the age of a primary schooler. Taking advantage of this, Chisame took various pictures of herself in this form for her webpage and dubbed herself; "Chibi-chiu; Chiu's little sister".