Ayumu "Osaka" Kasuga

Unlike the stereotypical Osakan, she seems slow and easily distracted, but she merely has a mind that works quite differently than most people. This makes her prone to daydreaming, absentmindedness, and non-sequiturs, but it also makes her unusually good at answering very specific types of riddles. Her unusual way of thinking gives her a very vivid imagination and a unique way of seeing the world.

Osaka often acts stuck in her own world. Although she seems slow and easily distracted, she merely has a mind that works quite differently from that of most people. Though she is often prone to daydreaming, absentmindedness and non-sequiturs, it also makes her unusually good at answering certain types of riddles. While some people assume that she lacks focus, the truth is that in quite a few cases, Osaka is really a little too focused. When she daydreams in class, she tends to dream about Chiyo and her pigtails either controlling her, giving her the ability to fly, keeping her alive, or being replaced with new ones. When she gets a thought in her head, she tends to focus on it so intently that the rest of the world simply disappears, causing her to often miss what's going on around her (an example is in episode 2, when a cockroach invades the class and Tomo is enthusiastically and noisily trying to exterminate the bug, literally sending desks, and presumably students, flying — while Osaka is completely indifferent and only tries to "chase" eye floaters). In episode 6. Osaka kicks her shoe off to predict the weather for the athletic competition the next day, only for it to land on a truck; Osaka and Chiyo's faces tell all. t the same time, Osaka has a habit of being able to point out obvious things nobody else seems to notice (such as the fact that none of her core group of friends has boyfriends or the fact that Kaorin had a crush on Sakaki) and has surprising levels of knowledge on unexpected topics such as marine biology and obscure kanji. Osaka enjoys sata andagi, a type of deep-fried bun similar to a doughnut; In Episode 21 she excitedly and repeatedly says "sata andagi" while holding sata andagi. She also seems to have an obsession with sea slugs; In Chapter 3, she names her team "Team Sea Slug" while in Chapter 33, she plays with sea slugs she finds on the bottom of the ocean. In Episode 15, Osaka enjoys putting her face in flour in the obstacle course, only to lose her chance of winning. When participating in the bread-eating race, her concentration was trounced when the commentator listed the flavour of breads available, causing her to spend too much time deliberating which flavour to pick and, hence, coming in last. Furthermore, she was every bit as interested as the other girls to hear what Minamo Kurosawa had to say while drunk. On their first trip to Chiyo's summer home, Osaka proposed telling a scary story where all of the girls are murdered one by one, only to reveal that in the end, she was the one who killed them all. She also suggested placing cat corpses inside a cafe as an accumulation of the other girls ideas for their second-year Culture Festival, which included a haunted house, a cafe, and stuffed animals. In Episode 25 she dreams about meeting and conversing with Chiyo-chichi while studying in a classroom. In Episode 19, Osaka compares her yawns with that of Chiyo and Tomo.

Osaka hates spicy food and carbonated drinks. According to Tomo, she has a short tongue, and can't hold her breath for more than a few seconds. She is obsessed with splitting chopsticks cleanly and made up a "magic charm" where you got good luck if you managed to do it. Chiyo ended up using the same method when praying for her friends to have good results on their college entrance exams. In contrast to most of her peers, Osaka always keeps a quiet, accessible mood. It's extremely rare to catch her in a fit of anger or losing control (as seen in Episode 25 of the anime, when she sports a maniac grin after finally learning how to break a pair of chopsticks evenly, and gets mad at Tomo for not doing it properly). Osaka is allergic to pollen, like Yomi, and is known for sneezing in an unusually subtle way, going "Ay-tchoh" in the anime and "At-choy" in the manga.