"Takahashi Rumiko Gekijou Ningyo no Mori Specials" aka "Mermaid Forest" Episodes 12 and 13 are DVD-only OVAs that, unfortunately, did not improve in production values compared to prior episodes. Aware that this is part of an anthology,there's little expectation of an overarching story. What stood out though is the lack of internal consistency with how the rules work regarding interaction with the mermaid biology compared to prior knowledge assuming you have watched episodes 1-11. It gets more absurd as time passes, and here, it's no exception. Uninspired direction, uninspired dialogue, uninspired animation... you're better off reading the manga if I were you.