Gaen Izuko

Specialist in oddities. She heads a union of experts called the Gaen Network, and it has become difficult for experts not affiliated with the network to operate. She is a senior from Meme, Deishuu, Yozuru, and Tadatsuru's college days. She is the younger sister of Tooe and the aunt of Suruga. She first appeared in "Tsubasa Tiger." She is a main character in "Koyomi Dead," "Shinobu Mail," and "Ougi Dark."

She is over 30 years old but looks like a teenager. Despite wearing oversized clothes that seem ill-fitting, she manages to wear them well. She has a peculiar way of speaking, as if explaining her actions step by step. She generally prioritizes her own convenience and has a unique familiarity, which made her disliked by her juniors. She possesses knowledge and insight far surpassing Tsubasa, and her catchphrase is "I know everything." She is estranged from her niece, Suruga, due to family circumstances, and met Suruga through Koyomi's mediation in "Shinobu Mail," after making a promise with him during "Shinobu Time." During their meeting, she introduced herself as "Oshino's sister, Oshino Izuko," hiding the fact that she was her aunt. Unlike Meme, who was not tech-savvy, she owns five mobile phones and smartphones. In August, she collected the armor made from the flesh and blood of the original Oddity Killer, and in "Koyomi Dead" and "Ougi Dark," she had replicas of the enchanted swords Kokorowatari and Yumewatari, which were later returned to Shinobu.

Later, under the idea of transitioning her covert specialist activities to a public organization, she was also involved in the establishment of the Rumor Division.