Yuki Yoshida (吉田 由紀 Yoshida Yuki) was the childhood friend and ex-boyfriend of Mafuyu who died from an apparent suicide roughly half a year prior to the start of the series. He played guitar in a band with Hiiragi and Shizusumi.
Similar to Hiiragi, Yuki has long goldenrod dyed hair at the top with short light brown hair at the bottom and hazelnut eyes.
For clothing he wore a sea-green colored uniform along with black jeans. He wears three ring piercings in his left ear.
Yuki likes showing off. He is both a dominant and charismatic person. However, he is also very caring and affectionate towards Mafuyu and they are mostly seen being together. Yuki is also very observant around Mafuyu.
Yuki is mentioned by other people, mostly in relation to the rumours of him going out with Mafuyu in middle school. Yuki hung himself in his room while he was in a drunken stage.
Another rumour is that the reason for his suicide had something to do with Mafuyu.
After which Mafuyu found him and breaks one of the strings on Yuki's guitar.
From Japanese 由 (yu) meaning "reason, cause" combined with 紀 (ki) meaning "chronicle".