After defeating the demon king, you receive a curse that makes you get attacked by hordes of demon at night. You return to your home with your two loyal companions and keep away from civilization as you try to survive the horde. You'll need to gather resources, build up your defenses, and craft stronger items to have a chance at survival.
Chop trees, mine ores, hunt monsters and wildlife, scavenge, and explore various dungeons in the forest and defeat their bosses to earn crafting ingredients. These dungeons are dangerous and even contain puzzles.
The demon hordes also leave behind useful items if you manage to defeat them. Use them to defeat future hordes.
You and your two companions won't be enough to defeat the hordes that get stronger with each passing night. Fortunately, you'll meet Kyubi, a demon fox, that's looking for a mate. Train her to be your loyal companion ...