Kakeru, an energetic fourth-grade elementary school student, serves as a hero capturing Pipo Monkeys with his specialized Get Net tool. He maintains a friendship with the genius inventor Professor, who supplies technological support and gadgets for missions. The Professor's granddaughter Natsumi operates the laboratory, supporting Kakeru's activities while often treating him dismissively. Hiroki, Kakeru's classmate and best friend, acts as both rival and companion during operations. Kakeru harbors a small romantic interest in Haruka, a Hi-Tech Robot Battle champion who joins their group after touring conventions.

In the first season, Kakeru confronts global chaos caused by Specter, an evil monkey enhanced by the Professor's Pipo Helmet. He allies with others to capture Specter-controlled monkeys, defeats the Neo Pipotrons, and contains Specter. This arc reveals Specter initially used Natsumi's pet monkey Kuuta as a vessel.

The second season opens during peace following Specter's capture. Three mysterious monkeys incite new disturbances, reviving Specter and regrouping the Freaky Monkey Five, prompting Kakeru to resume monkey-catching. His team occasionally receives episodic aid from twins Satoru and Sayaka and their aunt Akie. The Pipotron Brothers initially assist Specter's revival before shifting to comic relief. Across both seasons, Kakeru's core mission persists: deploying the Get Net and the Professor's inventions to capture monkeys and thwart Specter's schemes.