Nanako Kuroi (黒井 ななこ Kuroi Nanako?) or Ms. 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. She is more like a friend than their 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. Still single, she is constantly online, even on Christmas and New Year's Day. When writing on the chalkboard, Nanako is able to become ambidextrous. She loves to watch baseball, and is a big fan of the Chiba Lotte Marines. Also, Nanako speaks in a fake Kansai accent (in the dub, this becomes a Southern U.S. accent).
A running gag within the series is whenever Konata and Nanako are both online together, Nanako tells her 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. She is also completely oblivious to Yui Narumi's marital status, often using Yui as a source of understanding regarding the life of being single.
Nanako's physique is average. She has very long, blonde hair, which she ties at the back of her neck, and her eyes are green. She also has a sharp tooth protruding from one corner of her mouth.
|Konata Izumi - Tsukasa Hiiragi - Miyuki Takara - Kagami Hiiragi - Ayano Minegishi - Misao Kusakabe - Yutaka Kobayakawa - Minami Iwasaki - Hiyori Tamura - Patricia Martin - List of Characters|
|Sōjirō Izumi - Kanata Izumi - Yui Narumi - Tadao Hiiragi - Miki Hiiragi - Matsuri Hiiragi - Inori Hiiragi - Yukari Takara - Honoka Iwasaki - Nanako Kuroi - Hikaru Sakuraba - Hinata Miyakawa - Hikage Miyakawa - Akira Kogami|
|Goldy - Cherry|
|Anime Only Characters|
|Minoru Shiraishi - Meito Anizawa - Daisuke Ono - Gotouza|
|Manga Only Characters|
|Kō Yasaka - Yamato Nagamori - Izumi Wakase - Fuyuki Amahara - Tamaki Yamanobe - Miku Busujima|