It's summer and Natsuru has just turned 11. But everything is going wrong. His mom won't let him keep a pet. His soccer team has changed coaches. The girls in his class are ignoring him. And his single-parent home has become lonesome since his mom is busy with work. His life takes a turn for the better just before summer break, when Suzumura, the tallest girl his grade, suddenly talks to him revealing a world that is way tougher than his, but also much more free and fun.