Summary:
・Wears labwear when playing video games
While Idia does not at first seem fond of his outfit during the Glorious Masquerade event, he has a voice line of, “these threads are pretty sweet, actually. It’s like I just got a new class in a video game.”
As the clothes they receive from Noble Bell College are closer to costumes than streetwear, it is possible that the design does not reflect his preferences for his personal wardrobe.
Idia refers to his stargazer costume as “SUCH an extrovert outfit” and says that it is fancier than his usual clothing.
The sweatshirt that Idia wears as a part of his school uniform is possibly an example of his personal wardrobe, but has maybe never been referred to in dialogue?
While not a part of his personal wardrobe, Idia says that he wears his labwear when playing video games (he has changed out the usual goggle lenses for blue-light-filtering lenses), with his pajamas underneath them.
Twisted Wonderland Reference Note 