Lingering By the Water's Edge

S1, E6: It's summer break, and they all go to the mountains to camp. Hikari and Akari learn about nature and are happy; Ioneous and Jennifer get drunk, and are also happy. The group decides to play a game in the dark where they're basically supposed to split up into pairs and stake a flag on a rock. Hikari and Takeru wind up together and the rest of the group has fun spying on them, until Ioneous in monster-form starts running around in a drunken fit, making them think they're being attacked.