During a walk Gil and Josef has found some strange cave in the forest. And of course Gil, being a silly yet curious guy, decided to look inside. And Josef had to follow his friend to make sure that cyborg won't get into troubles.
Sadly, both Monster Hunters didn't make it out safely, because the floor has cracked and they've fell down and fainted.
A few minutes later.. or maybe a few hours later they've woke up safe and sound.. But one "smaaaall" issue has caught their attention.. They've switched their species|. Josef, that used to be a mulnth, became a human being and Gil, that used to be in his human form, turned into a mulnth.
After some inspections they came to the conclusion that it was caused by some old magic that's hidden in the cave, maybe one of old artifacts that are hidden all over the world after the first apocalypse (many hundreds years ago the planet they live on was ruined, but now it's habitable again). Now they have to find the artifact, bring it to the Shadow city and turn its magic backwards... Poor guys just wanted to have a normal Vacation..