Author: Naehara Hajime
Available and partially translated in web-novel and manga formats.
Synopsis:Heal, the prince of the kingdom of Sanfaris was born with the unfortunate crest of Cave King.
Because of this crest, he was relegated to being lord of a remote island by his father the king.
Of course, there were no people there, and no trees or plants. It was an island with just a single cave.
However, the moment that Heal picked up the pickaxe inside of the cave, the Cave King crest was activated. Its effect was specializing in mining, allowing you to efficiently mine all kinds of ore.
Among the ore that could be mined on the island, there was ore that increased your magic and even ore that extended your lifespan
Heal would become so engrossed in mining, that he would eventually create the strongest country.
- Crapsack World: Not only are the many fantasy races and humans all at the level of "kill on sight" with each other, but the ecology is actively hostile. Crabs the size of men swarm beaches, birds the size of condors swoop down and snatch away children, though rare, creatures like a leviathan, a monster the size of a landmass, near impervious to magic and physical attacks alike, which love to go around chomping down on sea vessels, and turning their crew into undead, but as of the latest chapter (72 in the web novel), we've got "devil hoppers," a species of locusts. As if a swarm of locusts wasn't already sufficiently scary, these are acid-spewing, omnivorous locusts that explode when they die, can fly great distances and reach swarms big enough to block out the sun and turn the sky black!
- Defeating the Undefeatable: Heal manages to take down a Leviathan, a monster so big and powerful as to be considered a myth. And he did it in single combat!
- Fantasy Kitchen Sink: There's the traditional fare, goblins, orcs, dragons, dragonoids, chimera, leviathans, kraken, etc. but as of chapter 95, we're introduced to a sentient octopus that came from outer space!
- Forgiveness: Justified. Heal manages to build the population of his territory by welcoming all comers who are willing to cast aside their ancient grudges and start a new life, even those he personally has a grudge against, like the orc pirates. This does have limits. He will respond with appropriate force against the Always Chaotic Evil and hostile beasts.
- Happiness in Slavery: Predominantly in the "life debt" category. The various disparate groups submit and request Heal "Tame" them in gratitude for saving their lives in desperate straits, and so they can benefit from the perks of his [Cave King] crest.
- Heart Is an Awesome Power: During his 15 years at the royal palace, Heal was treated with disdain and considered the embarrassment of the throne because of his lackluster [Cave King] crest that nobody had ever heard of before, and the fact that the rest of his stats were abysmal, regardless of how hard he trained. When he's dumped on a rocky reef as his "territory" upon his coming of age ceremony, he goes to a small cave to seek shelter. Once inside, his crest activates, making him a magical and martial powerhouse within a matter of days!
- Innocent Fanservice Girl: The goblin survivors from the Beldan tribe are accustomed to mixed bathing and have little to No Nudity Taboo. As such, when Rienna and Fuel "evolve" into very attractive human-looking women, they still have no reservations about prancing around completely naked when the situation calls for it and are confused when Heal gets flustered catching an eyeful.
- Keystone Army: Discussed. Everyone on the Shiorel reef is well aware that Heal's [Cave King] crest is the main factor why the disparate groups can't take hostile action against each other. If something happens to him, there would be nothing to prevent the ancient centuries-long grudges from flaring up again.
- Massively Numbered Siblings: Heal is the 17th child of his father, the king, and he still has younger brothers and sisters!
- Precursors: Heal eventually finds hard evidence that Shoriel reef was once a mountain, and the cave systems that result from his excavations hold ruins of a previous civilization. Humans once ruled the whole world unopposed, and at peace, but multiple cataclysms forced them to seek shelter underground and then transfer bodies into stasis while placing their souls in animals, mostly slimes.
- Rag Tag Bunch Of Misfits: As of the most recent update, Heal's territory is populated by slimes, cave spiders, goblins, kobolds, and orc pirates, all forced to work together with Heal, a human, in charge.
- Rare Candy: Many different types of ore on the island give people different abilites: such as increased magic power, increasing one's lifespan, bringing the dead back to life, a race evolution and many more.
- Sudden Game Interface: When Heal goes into the Shiorel reef cave for the first time and picks up a pickaxe from his supplies, suddenly his crest activates, he gets an interface with his options, and a voice inside his head giving him an exposition dump.
- The Unfavorite: Heal, the 17th prince and Rienna, (formerly Ri) of the goblins were looked down on by their entire families for being the weakest of their respective royal families. Upon arriving at the Shiorel reef, this changes.
- X Meets Y: Fans note that the story is basically That Time I Got Reincarnated as a Slime meets Minecraft.