The absurdity never stops escalating: a father-son duo whose entire fighting style revolves around butts, genuinely committed to the bit across a full series. It takes the Shin-chan formula of anarchic humor and weaponizes it, turning ridiculous premise into actual narrative momentum. You watch Lone Wolf defend his family against armpit-swordsmen with complete deadpan sincerity, and somehow that's exactly what makes it work.

Hiroshinosuke Nohara, known as the Lone Wolf, is a master of the butt-sword style who roams with his family looking for work. Along the way they meet a mysterious girl named Hazumi and a wild dog called Shiro, and the group decides to travel together. Assassins of all kinds come after them, and the danger peaks with the armpit-swordsmen of the Demon Bull Clan, sworn rivals of the butt-swordsmen. Facing one oddball foe after another, Hiroshinosuke and his son Shinnosuke get to show off their swordplay in a comedic action spin-off built around one question: butts or armpits?