Kuroi-sensei

Kanji name: 黒井 ななこ

Romaji name: Kuroi Nanako (Nanako being her first name and Kuroi her surname)

Gender: female

Age: 27

Birthday: February 8

Birthplace: Kanagawa Prefecture

Blood type: O

Height: 171cm (5'7")

MMORPG nickname: Nanakon

Nanako Kuroi/Ms. Kuroi/Kuroi-sensei/Ms. Nanako Kuroi is the world history class teacher at Ryōō High School.

Nanako is the homeroom teacher for Konata Izumi's class and her primary subject is world history. Nanako is more like a friend to her students than a teacher, as she has a lax personality. Consequently, she frequently borrows and exchanges video games with Konata, and is in Konata's guild in the same online game, where she plays as a scout. Nanako is constantly online, even on Christmas and New Year's Day, especially in the hypothetical case that she is single. When writing on the chalkboard, Nanako is able to become ambidextrous. Nanako loves to watch baseball, and is a big fan of the Chiba Lotte Marines. Also, Nanako speaks Kansai-ben despite living near Tokyo (this trait of hers is commonly referred to as a fake Kansai accent despite being more of a dialect than an accent). When speaking English, Nanako has a subtle southern accent and uses southern expressions from time to time.

Whenever Nanako and Konata are both online together, Nanako tells Konata to stop slacking off. This extends to within school as well, where Nanako often leaves Konata with a swelling on her head in order to keep her focused in class.

Nanako is completely oblivious to Yui Narumi's marital status (Yui is married), often using Yui as a source of understanding regarding the life of being single.

After Konata's class graduated, Nanako became the homeroom teacher for Yutaka Kobayakawa's second-year class.

Nanako has very long, blonde hair, which she ties at the back of her neck in a low ponytail with a blue bow, and her eyes are green. Nanako has large breasts. Nanako’s canine teeth are sharp.