It's allowed in my school to bring and consume homemade food and beverages as long as they are not consumed during classes/lessons, it's just so dumbfounding to me that the teacher would confiscate the tea and umeboshi from Hinata, like what's the point? They are not even harmful/illegal substances also not disrupting the classes or being a bad influence or anything. It's probably just some sort of Japanese culture/ideology, but I honestly don't get those pointless rules that are set just to "hammer down the nails that stick up".
Anyway, thanks for the additional page at the end that provide the references/glossary with pictures~ That's some passionate dedication I appreciate! Those are some really good looking well-balanced diet, looking back at my primary school lunch diet the menu was pretty plain and not nutritious at all compared to that, though it was a different time in a different country so it can't be helped...