|Unusual Features|| -Tsundere|
-Always refers perverted things as "shameless"
|Relatives|| Yuu Kotewaga (Brother)|
Mother and Father (unnamed)
|Education||Currently attending Sainan High School|
She is a very high-strung girl, has a very strong tsundere personality, and is very strict against improper behavior. Like most of the other girls in the series, she also becomes a love interest of Rito, although she is more reluctant to admit it to herself than most of them, due to her tsundere personality.
A common gag is that newer characters cannot remember Kotegawa's family name, calling her "Kokegawa" instead, presumably due to the fact that she is generally an unwilling participant in Lala's frequent schemes. More recently she's been called "Shameless Senpai" by Mea due to saying "Shameless" all the time, although this name may give the wrong idea about her.
Yui has long black hair and dark brown eyes, she is often seen with an angry or unpleasant face. According to Mio Sawada, her measurements are B88-W59-H87, an attractive figure compared to other students (something that other characters like Nana and Haruna feel jealous of), which is surprising and ironic considering her rejection of sex and courtship. Yui herself confirmed that she started wearing bras in middle school showing that she was a early bloomer.
- ―Yui's trademark word
Yui Kotegawa is a high-strung and uptight girl, she has little to no tolerance for anything perverted, people who bring personal items to school, misbehaving, or whatever she does not consider to be "acceptable behavior". Her opinions, quick temper, and habit of speaking her mind often results in her vocally reprimanding classmates. Yui quickly grows annoyed and disgusted by eccentricities and bizarre actions, especially with regards to Rito and Lala.
Unfortunately, almost every encounter with Rito usually ends up with her embarrassed, naked or groped (sometimes all three combined), and although her nature prevents her from easing her behavior, she does slowly warm up to his usual antics. After Rito saves Yui from a group of delinquents, she develops feelings for him. Her inexperience with boys leaves her unable to understand her own feelings and continually denies them to herself.
When Rito usually asks what's wrong, she says the exact opposite of what she wants to say and then yells at him in some way (a typical Tsundere), she tends to blush whenever someone mentions him and also thinks about him through something irrelevant like when Risa asked if she had anyone she likes or him complimenting on her yukata or even when seeing Riko. For some time now she has come to realized that she is in love with Rito, a fact she is annoyed about given her opinion of him. Deep down (despite being strongly against lewd things) she actually desires to do these things with him, one time during one of Rito's accidents she offered herself to him, on the condition that he would only ever do it with her (To-Love-Ru Darkness Chapter 3). This may also be a hint which shows her hypocrisy towards things she considered "shameless", or this is just a typical trait of those who are tsundere. She has been seen fantasizing about being together with him and Celine, as his wife and being pregnant with his child.
Eventually Yui gained the ability to recognize Rito's trademark clumsiness that she witnesses whenever he trips, even when he is disguised as someone else.
Despite her seemingly cold and stern facade, Yui is in fact a generally kind and sweet person at heart.
She also really likes cats – owning cat based books, having tons of stuffed cat dolls which she decorates her room with along with other cat shaped things, shaping her Valentine chocolate into a cat's face, and even having a cat-themed floaty, something Rito seems to find cute about her. She would secretly go to pet stores to look at cats, she would get embarrassed if anyone were to find out about this.
In her childhood, Yui despised all boys because of how violent, insensitive and above all shameless they can be and stated that they caused her much hardship as a class rep in 5th grade. She would try to protect girls from boys who would do these things to them, and because of this she thinks that any kind of love or romance is shameless since it meant being close with a boy. Her view of this changes slightly when she first met Rito. She saw him willingly saving a cat from a tree, the same cat she was unable to save and no other boy she asked even cared (although it was a few years later during a flashback that Yui remembered this event and Rito's being in it. Rito probably isn't aware that Yui was that same girl he met, it's unknown if he still remembers her). Yui had the impression that all boys are bad but because of Rito's bravery and kind nature, her impression of this changes and realizes that not all boys are bad (but still finds most of them shameless, even Rito, but understands very much that it's not really his intentions).
- Kotegawa has a cameo in Mayoi Neko Overrun! (Chapter 4, Page 33).
- Like many other anime girls (and some guys), Yui entered Saimoe Contests.
- Kotegawa is arguably one of the most well-received and popular female characters of the cast. In one online poll of all the females, Yui came in first, with at least 50% more votes than the second place.
- During a time when Yui got turned into a younger version by the Skunk of Youth, which was about 10 years old, when Peke shrunk her clothes so they could fit, it revealed that Yui was able to wear bras at the young age.