"OK guys, so we're making one last episode as an OVA. Should we continue the story?"
"Nah, lets just send all the characters to an island for no apparent reason where they can dance around in bikinis!"
Yep, the show addressed the stupidness of this situation itself in a comment from one of the characters at the start and yep, given the priorities of the show I should have expected a big fat slab of fanservice. But...to this extent?
If you like the show be rest assured you can safely watch this without missing out on anything. Nothing happens. The characters just get high and think they're shagging each other and....yeah.