|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 had more or less squandered her chances of being with him.
Chapter 100, 101
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.
Kotomi is introduced as a girl who holds a deep seethed grudge against Tomoko, considering her a bitch and human trash. The two share a common anime interest but this doesn't bring the two closer as Tomoko openly laments that only kids watch cartoons. It is later revealed that the two of them ended up attending the same high school. Tomoko doesn't remember Kotomi at all though, further angering her former classmate.
As of recent chapters, however, Kotomi's relationship with Tomoko has become a friendly one, although it's possible they don't even realize this. The changes are better shown on chapter 57, 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 Yu 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 Yu herself, which leads her believe the duo to be great friends because they go to the same school.
On chapter 64, Kotomi spends August 4th catching bugs with Yu and Tomoko, keeping afterwards a centipede she found, and on August 10th the trio goes to a polluted beach which Tomoko choose for being close-by. During the "beach trip", Yu becomes emotional over the time they're 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 Yu 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.
On 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, one moment genuinely enjoying each other's presence and afterwards being at each other's throats. Simply put, their relationship developed from simply hating each other to being "frenemies", which was prompted by Yu's sugggestion that they should get along on chapter 54.
- Kotomi is an anagram of Tomoki.
- "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/Yuu-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."