its just fair play. demons deceive humans by utilizing words conveying "emotions", frieren limits her magic output because demons are pride in their magic and would never dream of doing that. of course this is true for every mage, but demons are especially prone to that
@kalton @F1l1p34 if i remember correctly, the girl with the 2 umbrellas is the cosplayer girl and the guy is the classmate who has a crush on crossdressing MC. the 2 girls might be random, or they showed up in the chapter where they had PE class