Heal is the 17th prince of the Kingdom of Sanfaris. Besides being far down the line to the throne, he has a useless crest: "Cave King". So he is exiled to a tiny, deserted island--nominally to rule it, but surely to die of starvation when his supplies run out.
Entering a cave on the island, he finds an abandoned pickaxe. When he picks it up, he hears a voice: "You possess a tool that makes mining possible." With this, he will be able to dig out huge sections of the cave, collect everything into an inventory, and make use of the extremely valuable materials he uncovers. With the help of the "Cave King" crest, he might become a powerful ruler to exceed even his father.
The story in the beginning reads very much like someone novelizing a game of Minecraft--Heal digs up so many hundreds of stone, dirt, etc., and then the next day he does it again, but better. Eventually, more characters appear, and at length the story begins to pick up.
By chapter 100 or so, the story is a bit interesting, but it's really a trial to get that far.
|Shousetsuka ni Narou||Publisher|