A friend of Koiwai and Yotsuba, having known Koiwai since they were children. Standing 210 centimeters (6 ft 11 in) tall, he dwarfs the other characters, most notably Yotsuba. He is always called by the nickname "Jumbo," and when Fuka overhears his real name (Takashi Takeda) she seemed unimpressed and called it "common". He works as a florist at his father's flower shop, a formerly unmentioned occupation that Yotsuba and Fuuka only discover when they met him there by chance. Jumbo helps the Koiwais move in and frequently visits their house (usually bearing small gifts and treats for his best friend's child such as ice cream and picture books); he is more or less treated as a member of the family by Yotsuba. His dry wit and penchant for making deadpan quips can be confusing to the other characters but he usually means well and is very kind especially towards good-natured youngsters like Yotsuba and Ena.
At the same time, he is rather impulsive, and often really goes all-out in organizing impromptu activities for the younger children such as catching cicadas, fishing and star-gazing. During one of these encounters, he enters into an immature one-sided rivalry against Miura which resulted in him spending a single day in Hawai'i just because he was told that she will be going there during the fall season. He also develops a deep infatuation with Asagi when he was introduced to her, but is too shy and awkward around beautiful women to directly act upon it. As a result he often devises ways of taking advantage of Yotsuba's close relationship with Asagi as an indirect method for him to improve his chances. Unfortunately, due to the little girls naivety on such matters, these underhanded schemes are never effective; uninvited people usually get mixed in with the planned activity much to Jumbo's annoyance. Despite this, these forced encounters paved the way for him to be better acquainted with the other characters such as Ena, Fuuka and Miura.
Miura Hayasaka (早坂 みうら Hayasaka Miura?)
Ena's close friend and classmate who lives in a nearby high-rise condo. Miura is tomboyish and brusque, in both her appearance and speech (this is very noticeable in the Japanese version; see gender differences in spoken Japanese). She maintains a shorter hairstyle, often dons athletic apparel (such as jerseys of the Los Angeles Lakers and Los Angeles Dodgers) and is never seen dressed in overly girly attire. Jumbo once greeted her as Lamborghini Miura and then asked if she was a girl (Miura was wearing not-so-boyish clothing that day) much to her chagrin. Keeping true to her active nature, she was once seen using roller shoes; had a lively participation as a priestess at the local town festival; and is quite skilled at riding a unicycle. Most of the time, she can be brutally honest and callously frank; Miura tends to verbally retaliate in a tsukkomi-like manner whenever she feels wrongfully treated or ridiculed. Because of this mentality, Miura is depicted as a lot less kind and thoughtful youngster in comparison to her best friend Ena. A notable example: prior to the fireworks display festival, Jumbo was not being very polite towards Miura and in turn she was able to deduce the big guy's major crush on Asagi; Miura used this discovery to her advantage by making the hopeless romantic do all the spending on the premise of allowing Jumbo to indirectly gain favorable vibes with Asagi through her.
Yotsuba is also sometimes playfully teased by Miura even up to the point where the little girl is on the verge of tears; Ena always has reliable counter-measures on hand if her friend's pestering goes overboard. But whenever her mischief and ire are mostly held at bay, she really is a good kid deep down who is courteous, appreciative and repentant; Miura, Ena and Yotsuba are often seen spending fun times together and they share a close bond as good friends and constant playmates. In contrast to her rather masculine demeanor, Miura is surprisingly very squeamish. When Jumbo took the younger children fishing, Miura vehemently refused in continuing to use the live bait then opted for salmon roe instead (a luxury according to her); she ultimately distanced herself from the sight of Jumbo and Ena fearlessly gutting and cleaning-out their still wriggly catch. She was also terrified by a large frog that Yotsuba brought home to the Ayases. In a later chapter, Miura immediately turned tail and ran away on instinct when she saw Yotsuba nonchalantly holding a worm with her bare hands.
Torako (虎子?)
A close friend of Asagi who also attends the same nearby university; the two young women frequently plan trips and hang out together. Focused on being 'cool', Torako smokes cigarettes constantly and is very skinny. Her name means "tiger" (虎 tora?) "girl" (子 ko?) and Yotsuba enjoys calling her as just Tora ("tiger"). She is fond of dabbling in amateur photography using her old SLR camera and is the only member of the younger cast shown driving a car. Jumbo has yet to meet Torako and was quite apprehensive upon assuming that she is male and Asagi's boyfriend. Generally humorless and diligently adhering to a no-nonsense mentality, Torako was initially irritated and even exasperated by Yotsuba's quirkiness and antics. Admitting to Mr. Koiwai her troubles in dealing with young children, Torako then told him that Yotsuba is an exception; she eventually began to like the little girl and now considers being around her "fun."
Yanda (ヤンダ?) , actual surname Yasuda (安田?)
Yanda, is a friend of Koiwai and Jumbo. Though mentioned in the first and fourth chapters, when Jumbo calls Yanda "no good" for making lame excuses for not helping the Koiwais move, he does not appear until chapter 30. He is somewhat childish, as shown by the tit-for-tat pranks he plays on Yotsuba, including bribing her with candy then taking it back when it does not work, eating her ice cream, and prank-calling her, and is shown enjoying teasing Yotsuba and acting as her "nemesis". Koiwai refers to Yanda as his kōhai, but in what context he is Koiwai's junior is unknown. He is living from paycheck to paycheck, telling Koiwai that he eats instant ramen because he does not get paid until the end of the month, and only eating frozen meals the rest of the time.
Hiwatari (日渡?) / "Miss Stake" (しまうー Shimaū?)
A friend of Fuka's, given name unknown, who is in the same homeroom. Her first official appearance is in chapter 45, when she visits Fuka's home and recognizes Yotsuba from her trip to their high school in chapter 40. Hiwatari has a somewhat eccentric personality. She is normally called by her nickname Miss Stake (しまうー Shimaū?) due to a "mistake" she made when she first introduced herself to her class (in Japanese, shimau used as an auxiliary verb can mean to do something by accident, hence the pun).
