Uchi no Seiso-kei Iinchou ga Katsute Chuunibyou Idol Datta Koto wo Ore Dake ga Shitteiru.

A chuunibyou girl calling herself the "Nightmare of Calamity"—also known as Mea.

She was once Kurusu Reiou's former troublemaking friend. They spent precious time together, taking pictures of her, uploading them to social media, and making them go viral, even though Rei didn't even know her real name. This continued until Mea was scouted by an agency and left their hometown.

Eventually, Mea made her entertainment industry debut as a chuunibyou idol. However, after Reiou entered high school, he discovered that the class president, Juunaya Nagi, was none other than Mea, who had graduated from her chuunibyou phase. Due to certain circumstances, she needed to become the student council president as a first...