Only I Know That Our Innocent Class President Was Once a Chuunibyou Idol.

“Nightmare Disaster”, or just "Mare," was a "chuunibyou" idol who once took the world by storm. Leo, who used to work for her — taking photos and posting them on social media, trying to make them go viral — reunites with her in high school. However, she has outgrown her “chuunibyou” phase and she's now just Nagi Juunana, the socially awkward, introverted class president! What’s more, when Nagi wants to run for student council president — she asks for help from Leo, and he finds himself managing her career once again…!?

(Source: Kodansha, translated)