Gariben
The gariben (ガリ勉) is the Japanese variant of the classic “nerd” stereotype. The term was originally written as 我利勉 (lit. "self-interested endeavorer"),. But nowadays, it is partly spelled with katakana as a pun on garigari (ガリガリ), an onomatopoeia for scraping or crunching, which can mean "toiling," "cramming" or "grinding" in the context of working really hard.
While “nerd” has become synonymous with “geek” in the Anglosphere, with both terms now associated with niche hobbies like comic books and video games, gariben are focused entirely—and obsessively—on academics and studying, often to the detriment of their physical health and social lives. Given the meritocratic nature of Japan’s education system, it’s unsurprising to find students like this both in fiction and in real life. The term also can be used derisively towards someone who's overly intellectual or preoccupied with academics, as one might call someone an "egghead" in Anglophone cultures.
Gariben are best recognized not only by their piles of textbooks and flash card rings, but thick reading glasses and a concentration-filled expression. They may also wear a hachimaki band while they study, and can be found attending cram school or gifted student programs. They may or may not have a kyouiku mama.
Relevance to Eyeshield 21
Yukimitsu is a model example of a gariben, raised by his kyouiku mama to study constantly and shun any socializing and activities that aren't directly tied to academics. One spectator even calls him a gariben as he makes his debut during the Shinryuuji Nagas game.
This has taken a noticeable toll on Yukimitsu's long-term physical development, leaving him with a frail body that has very limited strength and endurance. Even after joining the Devil Bats, his efforts to self-improve are consistent with unhealthy gariben habits, such as exercizing for long hours and memorizing books full of plays well into the early morning. It's not unusual to find him sleep-deprived.
Yukimitsu also demonstrates more genera nerd traits, such as wearing reading glasses and having a flashcard ring in hand. His book bag is stuffed with textbooks, dictionaries, and study guides that he lends out to classmates. He occasionally wears a hachimaki while studying next to tall piles of books.