Rumic Theater is simply a show devoted to the telling of short stories by Takahashi Rumiko. Since the manga relating the bad stuff which happens when a commoner consumes mermaid flesh was released periodically by Takahashi as stand alone pieces, the producers of Rumic Theater decided to compile them all and meld it together for the second season.
Once again, Mermaid Forest ain't for kids under 8. If you're protective of your kids, it might not be for folks under 15. You're not gonna find characters like Shampoo, Ukyo, Ryunnosuke or Ran (my favorite Takahashi characters) in the second season of Rumic Theater. Though there is a fair amount of bloodletting.