The Odd Jobs gang has gone to the mountains to go hunting for matsutake mushrooms. Gintoki is in high spirits, but a hunter named Marinosuke appears before him and warns him to leave the mountain quickly because it's dangerous. But Gintoki and the others don't listen and are intent on finding matsutake mushrooms. Masamune, a giant bear that's being controlled by a space mushroom, appears before the group! Gintoki and the others escape thanks to Marinosuke. They try to fight Masamune to collect a reward. But a mushroom just like the one controlling Masamune is growing out of Gintoki's head!!