Komachi Hikigaya is Hachiman's younger sister. She is also a member of her school's student council.
Komachi appears to be a normal middle school girl of average height. She is usually seen wearing her middle school uniform. She has short-medium length black hair. Just like Hachiman, she has a strand of hair standing straight from her head (ahoge). In the light novel, it was mentioned that Komachi is flat chested even for a middle school student, but this is overshadowed by her outward personality.
Unlike her brother, Komachi has a cheerful, lively and forgetful personality which was shown when she revealed she ate the sweets her brother was meant to get from Yui and not telling him about it. Hachiman considers his sister to be an idiot and fool, at least when it comes to education. Komachi often borrows from his old projects and asks him to help her study.
She enjoys teasing her brother as she often tries to set up reasons to get him alone with Yui or Yukino. She is sly in handling things like setting her brother up in a date like situations or tries to get things in her favor. Unknown to her, Hachiman is actually well aware of her tactics and tries to go around it as Komachi gets frustrated with him, thinking he is unaware or because of his lack interest in it.
According to Hachiman, she's got the Big Three: cuteness, prettiness and good looks. Komachi is known for her charming personality which seems to attract everyone. Because of this, she mentioned to be a popular girl in her school despite the fact that Hachiman is her older brother (who was unpopular and not very well-known). Although mentioned to be popular she is only shown to hang out with Taishi.
She is a kind and caring person with an easygoing personality. This can be seen when she requested help from the service club for Taishi and also in Chiba summer camp where she helped the elementary school students.
She can also be serious and cold to people. In one incident, she refused to speak to her father for reasons unknown, which reduced her father to tears even to the point of him begging her to talk to him again. She also refused to talk to her brother Hachiman when he was rude to her when she tried to help him until he consulted her for advice and apologized.
It is mentioned in the light novel that she often spends all weekend at home with her brother. Being aware of both the merits and demerits of being social and loner, she chooses the best options that favors her and also chooses when, where, how and to whom she must socialize.
AbilitiesShe has very good cooking skills as she is usually the one that creates meals for herself and Hachiman. This can be seen in OVA. She knows Hachiman's likes and dislikes when it comes to food and people. She seems rather perceptive of her brother as she is able to notice that Hachiman had done another social suicide even though she was not present at the time. She is good at taking care of Hachiman and knows most of his needs as quoted by Yukino.
It is mentioned that she goes to the same middle school that Hachiman went to. She also aims for Sobu High because her brother is there. But her reason seems to be rude. She says that she will look like a nice girl in everyone's eyes in comparison to her brother. She was treated like an angel in middle school for having to "put up with" her brother.
Komachi innocently revealed that Yui came to visit Hachiman as a thanks for saving her dog with sweets but couldn't meet him because he was "sleeping" at the time. Komachi mentioned that she (Yui) would thank him at school personally since they go to the same school and handed Komachi the sweets which she ate herself and forgot to inform Hachiman (until they met again in Episode 5).
One time Komachi ran away from home once because she hated returning to an empty house. It was Hachiman who found her and he has been returning home before her ever since. However, in light novel it was mentioned to be a lie told by Komachi to make Saki understand her brother's concern over Saki.
In drama CD, it was mentioned that in middle school, Hachiman gave a present to the girl whom he liked on her birthday, by staying up all night compiling a bunch of anime songs to recommend. His present was accepted, but tragedy occurred the next day. At lunch time, in the PA system of the school, the broadcast committee chose his song by saying : ‘Aaaand the next song was requested by Class 2C’s Otagaya Hachiman-kun (snicker), a love song (snicker) for Yamashita-san!’.
After this incident, the name Otagaya passed on even after his graduation, to which Komachi expressed her difficulty in pretending that Otagaya was not her brother.
She used an underhanded method in securing her victory in student council membership. She openly announced her wish to everyone in class about joining the student council, thus prevented others from contesting in concern for their social standing and to avoid bad rumors about them of snatching away komachi's dream.
In Episode 5, Komachi get the Service Club to help her friend Taishi, with solving his sister's problem. She also reveals to Hachiman that Yui is the owner of the dog he saved.
In Episode 7, Komachi tricked Hachiman into going with her to Chiba summer camp for a summer Service club activity.
Komachi went to Sobu High school's cultural festival to explore the place.
In Season 2 Episode 3, After the field trip, Komachi asked about Hachiman's odd behaviour with the intention to help him. Hachiman was unable explain and rudely stated Komachi should mind her business. Komachi then angrily storms off and refuses to speak to him until later in the series when he apologizes.
They finally reconcile after Hachiman apologized and asked for her help. Komachi realizes her brothers issue in wanting to protect his friends. Komachi makes a personal request to Hachiman to stop Yukino and Yui from becoming student council president, in order to save the service club from disappearing which Hachiman succeeds in.
In the series she is shown to study hard for the entrance exam of Sobu High. In Episode 13 of Season 2, she was going to take the entrance exam of Sobu High School.
- "Is my mouth jammed?" (referring to jam she has on her face). Komachi to Hachiman
- "Komachi -teki ni point ga takai."Komachi to Hachiman
- "Oni-chan,What are you saying?,You dumbass! Nitwit!, Hachiman!" Komachi frustrated with Hachiman's lack of interest in romance
- She was the Point of character for Tract 6 of drama bonus C.D titled Tatoeba Konna Birthday Song (たとえばこんなバースデーソング, "Birthday Song for you") of Volume 3.
- On Wataru Watari's Twitter Profile, his profile picture is the visual novel version of Komachi Hikigaya. It could be an indication that Wataru Watari's favorite character in the series.