Reiho Morisawa disguised herself as a boy to work at a mine. Her father has been dead, she doesn't have anyone except her mother that have illnesses. She works hard and takes care of her mother, becoming the backbone of the family.
One day, an accident happened. She found something strange — A portal frame — deep inside the mine. She touches it, the cave trembles, eventually crumbles. She hides inside the portal frame, rocks are falling and blocking the way. She faints due to a lack of oxygen.
She wakes in a strange cave filled with danger and wealth — strange creatures, magic crystals, and even ancient relics — her challenge was monsters, her hope was crystals.
With her pickaxe, she will 𝙙𝙞𝙜 𝙩𝙝𝙚 𝙬𝙖𝙮 𝙤𝙪𝙩.