For the majority of the series, both Yui and Daichi are third-years at Karasuno, and are captains of the girl's and boy's volleyball teams respectively. They both went to to Izumitate Middle School, where they became good friends and occasionally practiced volleyball together.
Their first interaction in the anime is in the fifth episode of season one, where she asks him about Karasuno's match with Seijoh the following day, and if he was nervous. He tells her about the new first years, and how he believes that if they prove effective they can win.
We see them again in the 14th episode of season one, 'Formidable Opponents.' Yui accidentally expresses her concern that the girl's volleyball team will continue their losing streak and not win in the Inter-high that was coming up. Daichi tells her to believe in herself, saying that "no matter how formidable and unbeatable, you'll never win if you don't believe you can." She remembers how he said the same thing to her back in middle school and quotes him, blushing. She takes these words to heart and uses them to inspire her team to work as hard as they can during their match in the following episode.
In the first episode of season three, 'Greetings,' Yui gives Daichi a good-luck charm for the match against Shiratorizawa. However, she states that "it's not just for [Daichi], personally," and was to bring the whole team good luck. Daichi thanks her and leaves, and afterwards Yui hugs her friend, flustered, who retorts with "I'm surprised you were even able to give it to him." When Karasuno wins against Shiratorizawa at the end of the season, he picks it up off of the bench were he'd set it and holds it out to where she's sitting in the audience, making her smile and tear up.
Yui often gets nervous and flustered around Daichi, often being clumsy, stammering, and struggling to find the right words to talk. Which could imply she has feelings for Daichi.
They're still close in the future and willingly spend time together, seeing as how they were drawn happily grocery shopping together. Possible implications of a relationship, though no specific confirmation.
DaiYui is a generally well-received ship with a small fanbase across different platforms. Fans of the ship find the interaction between the two endearing, given their comfort levels around each other and constant support of each other. Yui is implied to have a crush on Daichi due to her blushing and shyness when giving him the charm. Sugawara likely knows of Yui's crush and would approve of a relationship between them since Sugawara nudged Asahi away with a sneaky grin to give Daichi and Yui some privacy when Yui was giving Daichi the charm.
|SHIPS||het||BokuYukie • DaiYui • HinaYachi • ShouMika • TanaKiyo • YamaYachi|
|slash||AkaKen • AoFuta • AtsuAran • AsaDai • AsaNoya • AtsuHina • BokuAka • BokuHina • BoKuro • DaiSuga • HinaNoya • IwaKage • IwaOi • KageHina • KenHina • KinKage • KuroKen • KuroTsuki • KuroYaku • Kyouhaba • OiKage • OiKen • SakuAtsu • SemiShira • SugaKage • TsukiHina • TsukiKage • TsukkiYama • UkaTake • UshiKage • UshiTen • UkaTake • YakuLev|
|femslash||KanoYachi • KiyoYachi|
|family||AkiKei • AtsuOsa|
|cargo||Kenma x Video games|
|CHARACTERS||male||Kei Tsukishima • Kenma Kozume • Shōyō Hinata • Tobio Kageyama|