|Yui is the older sister of Ui Hirasawa. But instead Ui acts more like the "older sister" of Yui, since she is more responsible and mature enough to take care of her older sister. Yui is quite happy to be able to have Ui as a sister and loves her very much. This is proven when she decides to make a meal for Ui when she got sick taking care of her despite her lack of cooking skills compared to Ui. She even dedicates her very first song that she wrote for Ui.|
Yui and Mio are often known for not being on the same side. Mio's maturity often doesn't fit Yui's childish personality. Yui oftenly only wants to play and keeps on forgetting how to practice, which makes Mio often annoyed.
During their first meeting, Mio teaches her how to play the basics of guitar and teaching her the basic chords in guitar, which again Yui thought it was too tough for a beginner like her.
Mio even often got jealous of Yui for having a fast metabolism. Mio is very concerned of her weight and tries to eat everything that won't increase her weight, while Yui eats everything, but never had any increase in weight, making Mio more annoyed and jealous. Other words, because of these differences, they have made a close relationship between each other.
|Ritsu's first impression of Yui was that she was a clumsy, childish, and useless girl without tempo. But when Yui joined the Light music club, Ritsu stated that she misjudged her. Later they became really good friends. Yui and Ritsu have a lot in common, such as their lazy and laid-back attitudes. They also have a sweet tooth for Tsumugi's treats. Yui some times claimed that she thought that Ritsu was in the same boat as her and gets disappointed when she found out that Ritsu does well on her exams, and did care for her drums. In the anime, Ritsu had passed a flu to Yui which made the band frantic because their performance date was near.|
| Mugi first met Yui back in the light music club room and had spoiled her with sweets and drinks so that Yui would be interested to join the club. After joining, Mugi had done quite a lot of good action to Yui, such as lowering the cost of the guitar when Yui was about to buy her first guitar.
Yui always wanted to taste more of Mugi's cakes and could not wait to eat them, it is said that without Mugi's snacks, she would not be able to play the guitar properly.
Same like Mio, Mugi is very concerned about her weight, and would get very annoyed, wondering Yui's fast metabolism.
|After watching the Light Music Club's performance during the freshman reception, Azusa thought of Yui as a very talented guitarist, eventually this thought led her to join the club, later she regrets thinking highly of Yui and now thinks of her as a student who just likes to procrastinate. Azusa admires Yui due to her certain abilities, her ability to go far due to sheer determination and her ability of perfect pitch. Despite being better at guitar than Yui, she insists that Yui played the lead guitar due to her seniority (though in some songs, usually opening songs, Azusa plays the lead guitar instead) Yui had nicknamed her Azu-nyan (-nyan is a Japanese suffix associated with cats) after convincing her to try on a pair of cat ears and say "meow", this nickname was carried throughout the whole series, ironically, Azusa is not too good with cats. (despite being called Azu-nyan by Yui, Azusa doesn't even try to stop her, maybe this is a hint that Azusa "likes" being called a cat)|