Headcannon: I don't think Shuichi has a good relationship with food.
Unfortunately I also think this is probably canon. Maybe.
At the start of Chapter 2, the morning after Kaede's execution, Kaito pays Shuichi a visit and invites him to breakfast (kind of implying everyone has to be there for them to have breakfast), and then Shuichi goes "I don't usually eat breakfast so..."
Later in the same chapter, there's a nighttime announcement where the Kubz decide to do a cooking show thing and they make... wait, what did they make again? *checks notes* Spicy kimchi chicken & rice bowl... anyway, Shuichi's immediate reaction to this is "...I wouldn't eat that greasy food even if they threatened to kill me." Note that he specifies he wouldn't eat it because it's greasy.
Not sure if this is anything, but in Kaede's FTEs in the bonus mode, there's this moment where Kaede asks him what kinds of foods he likes, and if you answer vegetables (ahem, healthy vegetables), Kaede says "are you worried about your calorie intake?", and then Shuichi says "A little bit... I'm not athletic, I gain weight easily..."
On their own, these things aren't so bad, but together... I have concerns...
(I also have to wonder if Shuichi's parents both being in the entertainment industry have anything to do with this)
(I wonder if there are more moments that I'm forgetting)
