[Kumiko](https://anilist.co/character/798/)'s grandfather. A kind, wise old man who loves Kumiko very much, and is always there to support her and give advice. He took Kumiko in after her parents died. Though crime rookies might believe he is a man of little importance due to his yakuza branch only having a few members, he is actually highly respected in the underworld. 

Kumiko "Yankumi" Yamaguchi enters Shirokin High School to become a math teacher. She's assigned as the homeroom teacher for class 2-4, populated by a gang of delinquents.  At first, the class tries everything to rattle her cage, but to no avail. In a short period of time, Yankumi gains the respect of the class. But what the school doesn't know is that she's the heir to the Oedo Group, a powerful yakuzan clan. So while Yankumi struggles to excel in her career as a teacher, she must also keep her yakuza background a secret.<br>
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(Source: Media Blasters)

__Hobbies:__ Jazz & Tap dancing
__Nickname:__ 周ちゃん

Chikao Ootsuka was a Japanese actor, voice actor and narrator, with a career spanning 67 years.
Ootsuka died from ischemic heart failure at the age of 85 on January 15, 2015.

Father of [Akio Ootsuka](https://anilist.co/staff/95146/Akio-Ootsuka).

[Profile (aoni)](https://www.aoni.co.jp/search/ohtsuka-chikao.html) | [Wiki (en)](https://en.wikipedia.org/wiki/Chikao_Ohtsuka) | [Wiki (jp)](https://ja.wikipedia.org/wiki/%E5%A4%A7%E5%A1%9A%E5%91%A8%E5%A4%AB)

Fresh out of college, Kumiko "Yankumi" Yamaguchi becomes a math teacher at an all-boys high school. Unfortunately for her, she's assigned by the school board as the homeroom teacher for class 3-D, which happens to be the class of delinquent students. When the class attempts to make a living hell out of Yankumi's career, they fail as her persistence and aggression gain her respect. However, little does anyone in the school know that Yankumi is actually heir to the Kuroda Ikka—one of Tokyo's most powerful yakuza clans.
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(Source: Anime News Network)

Note: Chapter count includes 9 extra chapters in Volumes 9-15

Ryuuichirou Kuroda