|Family Members||Father, Deceased|
|Voice Actor||Mizuhashi Kaori|
Kotomi Komiyama (小宮山 琴美 Komiyama Kotomi?) is Tomoko and Yū's classmate in middle school, who appears in the spin-off manga. She and Tomoko do not like each other very much and are usually forced to get along with each other when Yū is around. She is later revealed in the main manga to have gone to the same high school as Tomoko, though Tomoko had more or less completely forgotten about her by then. She has a crush on Tomoki, but Tomoko seemingly more or less squandered her chances of being with him.
Kotomi was a middle school classmate of Yū and Tomoko. When introduced in the manga, Kotomi has a strong dislike for Tomoko which appears to stem from Tomoko comically ruining her attempt be introduced to Tomoko's brother Tomoki. For her part, Tomoko appears to have forgotten about her. The spin-off manga TomoMote which takes place during their middle-school years shows that she and Tomoko always clashed.
Kotomi is a shy girl but does not have the difficulty with social interactions that Tomoko has. Much of her character is depicted reacting to Tomoko, making her appear resentful, judgmental, and jealous. However, she appears a much nicer person to other people. She interacts with a potential rival, Akari Iguchi, for her crush.
Kotomi has shoulder-length black hair. Her main accessory are her glasses. Her dress varies from her middle and high school uniforms to more contemporary clothes outside of school. In high school, she mainly wears a sweater-vest over her shirt and tie with skirt. She dresses in her favorite team's gear when attending baseball games.
She does not appear in the first season or the OVA.
Yū ends up befriending Kotomi in middle school on a day when Tomoko had to stay home due to fever. The two have since been close and have kept in touch after reuniting. She seems to remain oblivious to the discord between Tomoko and her.
Kotomi is introduced as a girl who holds a deep seated grudge against Tomoko, considering her a bitch and human trash. Part of this comes from the shared rivalry for the friendship of Yū; however, Kotomi maintains a crush on Tomoko's brother Tomoki. Tomoko comically ruins an introduction between the two in middle school, and Kotomi has carried her resentment ever since. While Tomoko initially appeared oblivious of Kotomi's feelings for her brother, she will later use Kotomi's crush as an opportunity to torment her. In 83 when Kotomi reacts to learning that a girl has been visiting Tomoko's brother for some time, only to relax a bit when Tomoko tells her the girl has never entered her home farther than the entry way, Tomoko calmly teases Kotomi by saying, "Though they usually have sex in the entryway before she leaves."
The spin-off manga TomoMote reveals that the two always had bad relationship. Each begin to interpret any utterance or action by the other as an insult. Thus, in 15 when Tomoko complains about sweating in the humidity, Kotomi offers her deodorant which Tomoko immediately interprets as Kotomi stating she stinks. The two share common anime and manga interests but this does not bring the two closer as Tomoko initially ridicules that only kids watch cartoons. Tomoko does not remember Kotomi when she meets her in high school which further angers her former classmate. Further, Tomoko seems to make an effort to never remember her surname.
As of recent chapters, however, Kotomi's relationship with Tomoko has become more tolerant if not friendly, although they possibly do not realize this and would not admit it if they did. The changes are better shown on Chapter 52, when Yu decides the trio should spend the first day of summer break together. They run into each other at the bus stop and agree to go together to meet Yū in a cafe and, while the ensuing ride was obviously awkward, there was no antagonism between the girls. During the rest of the day, Kotomi and Tomoko end up paying more attention to each other than to Yū herself, which leads her believe the duo to be great friends because they go to the same school.
In Chapter 64, Kotomi spends August 4th catching bugs with Yū and Tomoko despite her declaring the activity both childish and gross. However, after Tomoko convinces Yū that a rhinoceros beetle is "cute" and she should keep it as a pet, Kotomi quietly catches a centipede which she keeps on her desk at home. On August 10th, the trio goes to a polluted beach which Tomoko chose because it is close. During this "beach trip," Yū becomes emotional over the time they are spending together and starts to cry, which causes the other two girls to panic. During August 17th, the trio heads over to Comiket, but Kotomi is soon left alone when the other two girls leave the place for it being "full of guys" and "stinking," although Tomoko tells Kotomi to call them when she's done. Kotomi seems to genuinely enjoy the time spent with Yū and Tomoko, as the only antagonism between her and Tomoko, open or otherwise, is during August 4th, but it's hard to say whether it actually meant something.
In Chapter 79, however, they seem to go back to being enemies. After Kotomi and an unnamed friend of hers find Tomoko alone during the school trip to Kyoto, she asks her friend if she can join them in what Tomoko describes as an condescending tone. Tomoko immediately spots her roommates and, in order to get away from the girls, joins them in exploring the city, which prompts Kotomi to follow her around, surprised that Tomoko actually has friends, much to her friend's confusion.
All in all, Kotomi and Tomoko seem to have a hate-like relationship, in one moment genuinely enjoying each other's presence and in another being at each other's throats. Simply put, their relationship developed from simply hating each other to being "frenemies", which was prompted by Yū's suggestion that they should get along in Chapter 54.
Kotomi has had a crush on Tomoki since she was in middle school with Tomoko and Yū. In a flash-back episode in the manga where Tomoko recalls her, she approaches Tomoko to meet him, Tomoko comically misunderstands and misrepresents her interest leaving Kotomi embarrassed. When she enters high school and renews her acquaintance with Tomoko through Yū, her crush continues. Her crush and attention appears one-sided for the first 100 chapters of the manga and. Much of the story at this stage involves a comic rivalry for his attention between her and Akari, both of whom Tomoko deems "perverts" and addresses them as "the dick sisters." Yet out of the blue in Chapter 108, Tomoki approaches first Tomoko then Akari to learn what type of person she is. In Chapter 112 she is comfortable enough to make and present him with chocolates with hilarious results.
- Kotomi is an anagram of Tomoki.
- Kotomi and Tomoko attend the same high school
- Kotomi is a devoted fan of baseball and the Chiba Lotte Marines baseball team.
- "People should recognize that some girls are just nipples and nothing else."
- (About Tomoko, Chapter 46) "That fucking bitch! She's trash, just like I thought!!"
- (Kotomi and Tomoko, Chapter 54) "Ah, this feeling again... It's just like the first time we talked to each other when Naruse-san/Yū-chan wasn't around. That's right... I never really wanted to get along with this person to begin with. But we just ended up trying to get along back then too."