Kyouiku Mama 

Kyouiku mama (教育ママ), or “education mom,” is a Japanese cultural stereotype of a mother who’s unhealthily obsessed with her child’s academic performance. She’s controlling and overbearing, forcing them to study excessively and attend cram school and other after-school programs. Children with a kyouiku mama may live in constant fear of her temper, which flares whenever they fall short of her high expectations. Her behavior often negatively affects the child’s physical and social development, as well as their mental health.
Kyouiku mama is similar to the authoritarian "helicopter parent" stereotypes of other cultures, such as the athletics-fixated American “soccer mom” or the Chinese “tiger parent,” who uses strict methods to ensure that their child overachieves in all facets of life. However, the kyouiku mama strictly forbids her children from partaking in any hobbies that aren’t related to their studies, including clubs and extracurricular activities.
While any mother of any appearance can be a kyouiku mama, the most familiar portrayal in Japanese pop culture is a middle-aged woman who ties her hair back in a bun, wears pointed cat-eye eyeglasses, and has a severe, no-nonsense demeanor. She may also speak in the antiquated, snooty Yamanote dialect to make her speech sound sophisticated.
Relevance to Eyeshield 21 

Yukimitsu’s mother, Akari, is modeled off the kyouiku mama stereotype. She’s forced him to attend cram school since he was a child, and strictly forbade him from extracurricular activities, including sports. As a result, he's grown up to be a model gariben with a skinny, frail body and no social life outside of academics (though the latter changed after he joined the Devil Bats).
Consistent with the stereotype, Akari's portrayed as an older woman wearing a bun and cat-eye glasses. Yukimitsu even dreads the day she’ll start adding ~zaamasu (ざあます) to the end of her sentences, a hallmark of feminine Yamanote speech.
Akari also has a nasty temper, as Yukimitsu imagines her screaming at him and walks on eggshells around her. For most of the series, he hides playing American football from her to avoid incurring her wrath. In a surprising twist, Akari happily approves of her son's new hobby after Hiruma poses as Yukimitsu's homeroom teacherand convinces her that playing on an all-star sports team will help his future job prospects.