Osomatsu-san follows the Matsuno household, where six identical brothers—self-centered Osomatsu, manly Karamatsu, voice of reason Choromatsu, cynical Ichimatsu, hyperactive Juushimatsu, and lovable Todomatsu—are all over 20 and still living like NEETs. Rather than building careers or taking adult life seriously, the sextuplets spend their days at home, chasing girlfriends, chasing easy money, and turning the smallest idea into a disaster. Even the rare moments when they decide to look for work usually end in embarrassment, because their personalities clash just as quickly as they do.
The series plays those failures as a string of absurd, often downright bizarre adventures. Whether the brothers are trying to improve their social standing, survive another humiliating interview, or simply get through an ordinary day without tearing each other apart, each scheme seems to unravel in a different way. What keeps Osomatsu-san moving is the constant friction between the brothers’ very different temperaments and their shared refusal to grow up, which makes even a simple errand feel like a chaotic battle for survival.