Red Peril Lava Cave is the seventh unlockable story-mode area in Osawari Island. It contains 20 different stages and is the home to Ruby-type Eromons. The legendary Eromon, Belial may also be found in any of the 20 stages.
"An incredibly hot cave where lava flows. Near the entrance there's a sight-seeing area, and the inside of the cave is full of ruins from ancient times."