Izuko Gaen is a highly intelligent and enigmatic woman in the Monogatari Series, known for her vast knowledge of oddities and the supernatural. Acting as an advisor and behind-the-scenes problem solver, she often assists the main characters with cryptic guidance and information that only she seems to possess. Gaen is the head of the 'Oddity Specialists' and is Shinobu Oshino's mentor. Her enigmatic personality and tendency to claim she 'knows everything' make her a mysterious and pivotal figure in the series.