She's a high school senior who first crossed paths with Mio after Sakura—Takahiro's horse—caused her some embarrassment in front of her underclassmen. Frustrated enough to challenge Mio to a joust over it, she lost but came away with genuine respect for her opponent.
She's got an odd mix of modesty and boldness going on. Getting seen in a school swimsuit mortifies her, but she'll confidently wear a thong during a joust without hesitation.
Coming from money, Bertille owns several mansions scattered around the school area. Wealth clearly isn't an issue for her.
Content compiled by AnimeList.moe from publicly available sources.
