I Am in a Different World, and I Can Change My Camp Freely!

Shipwreck, desert island, kobolds. Banner, who traveled through time again, thought he had gotten the worst start for a time traveler. It wasn't until he was knocked unconscious and taken away by two knights as a "living survivor" that he knew what it meant to be truly desperate. After waking up, a demon king's head wearing a helmet gave him two choices: join the demon king's army, or leave (dog leash). Just when the camp system popped up a prompt [reward increased by 10000%], Banner chose the former without hesitation. Wait... Why does the Demon King's Army have to meet every month? In order to survive, Banner sneaked into the Durang Chamber of Commerce and pretended to be the nephew of the late old guard. However, the saint who met the goddess during the mission said that Banner was a member of the Brave! When the final battle between the Demon King and the Hero began, Ban covered his face and said in a muffled voice: "Actually, I'm just passing by and you guys are talking nonsense...?"