Konjou Kasumi
Kasumi founded the Adventure Club and served as its first president. She's best known for being incredibly close with Ryuugajou Nanana—like, genuinely special friends in a way that set the tone for everything the club became.
When Kasumi graduated, she took off with the entire Nanana Collection they'd gathered together, which is kind of a big deal since that collection is basically the whole point of the club's existence. She's also responsible for writing the "Nanana Manual," the guide that presumably explains how all this treasure-hunting stuff actually works.
Content compiled by AnimeList.moe from publicly available sources.
