In the seemingly ordinary residential city of Urayasu in Chiba Prefecture, the Osawagi family turns daily life into a constant state of chaos and destruction. At the center of the mayhem is Kotetsu Osawagi, an impossibly energetic elementary school student whose boundless capacity for mischief drags his family, friends, and entire neighborhood into one absurd crisis after another. The manga follows no single overarching plot but instead thrives on short, self-contained gag episodes where anything can happen, from battles with rival schools to full-scale domestic warfare erupting over a television remote.

The cast is a rotating gallery of grotesque and exaggerated personalities. Kotetsu serves as the primary engine of destruction, a boy whose solutions to problems typically involve overwhelming force and complete disregard for property. His father, Daitetsu Osawagi, is a chain-smoking taxi driver whose temper is as explosive as his son's, often crashing through his own front gate in his haste to use the bathroom or engaging in bizarre contests with his friends. Kotetsu's closest ally is Doitsu Jin, a German-Japanese classmate whose strange appearance and deadpan reactions complement Kotetsu's wild energy. The family also includes Kotetsu's long-suffering mother and his baby brother, who is unnaturally strong and frequently beats up his older sibling. Their teacher, a perpetually put-upon man named Harumaki, often finds his attempts to maintain classroom order thwarted by the students' surreal behavior, making him a frequent victim of the humor.

The humor is aggressive, nonsensical, and often scatological, relying heavily on slapstick, gross-out jokes, parodies of Japanese popular culture, and extreme facial expressions. Despite the lack of a continuous narrative, several recurring elements function like arcs, such as the intense food battles between overweight children, the ongoing saga of the homeless man who lives in a makeshift shelter near the river, and Kotetsu's various schemes to acquire money for video games or snacks. The series gleefully subverts the notion of a peaceful suburban comedy, presenting Urayasu as a battleground of wills where the most unhinged and stubborn personality wins the day, leaving a trail of demolished walls and bewildered bystanders in its wake.