I actually just binged the manga adaptation and wow, the setup is a lot more methodical than I expected from an isekai. A regular office worker gets transported alone to a classic fantasy wilderness, but the twist is he gets a crafting-focused 'Survival Guide' skill instead of a combat cheat. The entire first arc is basically him learning to make tools, find clean water, and build a shelter from scratch. It's surprisingly detailed about the 'how' of surviving, almost like a wilderness manual with fantasy elements.
The plot really picks up when he accidentally creates a sustainable camp that starts attracting other lost people—a knight, a mage, a beast-girl—forming a little community. The story shifts from solo survival to managing this impromptu settlement, dealing with resource disputes, and uncovering why people are getting dropped into this world. The central mystery is less about a demon king and more about who or what is conducting this 'experiment' and why the main character's guidebook seems to have extra permissions. It's a slow-build story focused on community and problem-solving over big battles.