Otherside Picnic follows Sorawo Kamikoshi and Toriko Nishina as they move between ordinary Japan and the hidden Other Side, a dangerous parallel realm filled with creatures that can threaten anyone who enters it. Doors to that world can appear almost anywhere, from secret elevators to shrine entrances, and every crossing reveals a desolate landscape that is unsettling, fascinating, and hard to leave behind.
After a fateful encounter with a horrifying denizen of the Other Side, Sorawo is left questioning how much longer she wants to keep going. Toriko, meanwhile, is searching the realm for her friend Satsuki, who she believes is lost somewhere inside it. When their paths cross, the two women begin a cautious partnership that slowly grows into a close friendship.
To learn more about the obscure dimension, Sorawo and Toriko keep traveling back and forth between the real world and the other side, documenting what they find and trying to map a place that resists understanding. But the Other Side is not passive: their bodies are gradually affected by its influence, leaving them more exposed to the horrors ahead as they continue chasing the answers and the people that brought them there.