The Matsuno brothers try to adapt their show to contemporary times, with mixed results.

The Matsunos are invited to Hatabou's birthday part. Meanwhile, Iyami discovers that his buckteeth contain a rare metal.

The sextuplets catch a resilient cold. Later, the brothers question Todomatsu about all the things he hasn't told them about his personal life. Afterwards, Choromatsu plays a paranoid vice-principal overly worried about plans for his school's cultural festival.

Wanting to become the main protagonist of the franchise again, Iyami holds a bizarre kart race to determine who the protagonist of Osomatsu-san will be.

The 10-year-old Matsuno sextuplets of Osomatsu-kun are given a glimpse of the future and see they're going to get fat, greedy and beaten up by angry girls.

The prehistoric sextuplets return, partaking in dangerous sports. Later, in modern day, noticing their father acting strangely, the brothers discover that he is worried that there's not enough spark in his marriage. Feeling he should return to a more innocent time, the boys give their old man a masterclass in being a virgin, albeit with no success. After embarrassing himself in front of his sons, Matsuzou considers a love potion from Dekapan, but is this really the best way to patch things up with the love of his life?

The prehistoric sextuplets fool with nature for the last time. Several thousand years later, in a parody of Romance of the Three Kingdoms, Emperor Osomatsu and a group of bizarre generals attempt to take over the country. Meanwhile, in the real world, Osomatsu joins Todomatsu at a mixer, struggling to keep his perverted instincts in check.

Jyushimatsu befriends a young boy named Eitarou but gets called in by Eitarou's mother when he starts imitating him. Later, Dayon steals Dekapan's underwear, forcing him to give chase all over the city and universe while butt naked.

Ichimatsu becomes paranoid when lucky things happen to him all day, so he and Jyushimatsu try to punish themselves to balance things out. A lovey-dovey couple go to a hot spring inn that's haunted by a zashiki-warashi named Osoma.

Matsuzou becomes hospitalized, leading the brothers to seriously think about their lives and get proper jobs to support their family. A chance meeting with Totoko sets Osomatsu's mind straight...