"Osomatsu-kun: Suika no Hoshi kara Konnichiwa Zansu!" is a continuation of the classic "Osomatsu-kun" series, focusing on the misadventures of the Matsuno sextuplets: Osomatsu, Karamatsu, Choromatsu, Ichimatsu, Jyushimatsu, and Todomatsu. The story begins with the brothers encountering a mysterious watermelon-shaped spaceship that crashes near their home. From the ship emerges an alien named Suika, who claims to be a prince from a distant planet. Suika seeks the brothers' help to repair his spaceship and return home, but his presence quickly disrupts their already chaotic lives.

The narrative unfolds as the Matsuno brothers, known for their laziness and troublemaking tendencies, attempt to assist Suika while navigating their usual antics. Suika’s alien technology and unpredictable behavior lead to a series of comedic and absurd situations, often involving misunderstandings, slapstick humor, and satirical commentary on everyday life. The brothers’ interactions with Suika highlight their distinct personalities: Osomatsu’s laid-back leadership, Karamatsu’s self-absorbed theatrics, Choromatsu’s neurotic tendencies, Ichimatsu’s gloomy demeanor, Jyushimatsu’s eccentric energy, and Todomatsu’s cunning charm.

As the story progresses, Suika’s presence attracts the attention of various eccentric characters from the neighborhood, including Iyami, a scheming conman, and Totoko, a self-centered idol. These interactions further complicate the brothers’ efforts to help Suika, leading to escalating chaos and humor. The series maintains a lighthearted tone, blending surreal comedy with moments of camaraderie among the brothers. While the overarching goal of repairing Suika’s spaceship provides a loose narrative structure, the focus remains on the episodic and often absurd escapades of the Matsuno brothers and their alien guest. The series captures the essence of the original "Osomatsu-kun" while introducing new elements through Suika’s character, offering a fresh yet familiar experience for fans of the franchise.