Volume 1 Summary:
Up-and-coming pitcher Saiga Kanata is a battery together with his childhood friend Shinonome Haruse, who is also the baseball team captain and catcher. When they were kids, Haruse, who just moved into the neighborhood, started talking to the introverted Kanata. Ever since then, they grew up together like brothers: Haruse as the "older brother", and Kanata as the "younger brother". However, Kanata pines and lusts for his "older brother". Kanata broods, wondering how long their pretend-play at brothers will continue...

**"Nanahoshi" comes from the Japanese word for the seven-spotted ladybird, "Nanahoshi Tentou(mushi)".
A "battery" in baseball refers to the duo of the pitcher and catcher.

Volume 2 Summary:

Finally, Kanata confesses his feelings, and starts dating Haruse. Not long after, Haruse's younger brother who lived apart from him due to their parents' divorce, appears in front of Kanata, threatening to expose their relationship to the public if they don't break up before the start of the summer solstice. Kanata struggles to tell Haruse the truth...

Volume 3 Summary:

Thanks in part to Kanata and Haruse's achievements as a battery in their baseball team, they become representatives for Otaru City. As they're surrounded by girls from other schools, Kanata has a selfie taken suddenly and becomes a hot topic overnight. One day, the two are interviewed by baseball fan and local idol, Riana. During Kanata's shoot, Riana declares to Haruse that she's in love with Kanata. Haruse receives a shock from hearing this...