Lol feels like author used this as an excuse to put manga lunch stereotypes on display. They meticulously detailed everyone having a different type of lunch that reflects their personality and/or circumstances exactly.
From left to right, we have:
- Bento made by doting family member for Suzuki, as would be expected for any male in this world with a living family, probably.
- 2 dark colored (rye bread?) sandwiches and vending machine drink for the rather mainstream and mildly trendy twins.
- Standard sandwich and packet drink for the similarly positioned Kakizaki, but slight reversal of proper and trendy.
- Self-made bento for hinata, often a stereotype for family issues, besides being independent and mature.
- Cafeteria bought donburi, but with own bottle, probably with tea, and also extra milk (?) for Kana, reflecting the well-off but reasonably humble honor student.
- Heavy sandwich, might be yakisoba and packet drink for the laidback and carefree Miku who doesn't put much thought into her food.
MC makes their own food, as expected of the standard ever-reliable MC.