June 2021. Morishima Hotaka, a first-year high school student living on Kouzu Island, runs away from home and arrives in Tokyo by ferry. He lives in an internet cafe, but his cost of living is gone without a part-time job, and he visits a writer, Suga Keisuke, whom he met on the ferry. Keisuke and his niece Natsumi run a small editing company that contributes articles to magazines. Hotaka begins working there.

That summer, the Kanto region is experiencing prolonged rainy days due to unusual weather conditions, and ​There was a rumor about an urban legend that "100% Sunny Woman" which temporarily called for fair weather. Hotaka meets a girl named Amano Hina in an incident. She was the "Sunny Woman" and had the ability to clear the clouds for a short period of time by praying for a localized but certain break in the clouds.