Sanematsu wakes up in Osomatsu's world as the seventh Matsuno brother. After spending several weeks of happiness with the siblings, Sanematsu eventually realises it was all a delusion he had been experiencing after ending up in a car accident. Jyushimatsu, Iyami, and Hatabou go on an expedition to find a Super Mongolian Death Worm. Choromatsu changes up his image by dying his hair brown, making it hard for his brothers to tell him that it's doesn't actually make him look cool.