The mod follows you, the main character (MC for short), as you help the literature club (Natsuki, Monika, Sayori, and Yuri) create a wonderful stall for the school's summer festival. The literature club decided to create multiple literature works to contribute to the stall, with you playing as support to one of them.
…And so the MC chose to support someone he has always wanted to get closer to: Natsuki. MC has promised her the absolute best-est manga writing that it would blow the entire universe!