The distant future, long after the Western calendar is no longer used. Humans live shoulder-to-shoulder, cramped in the "Labyrinth," an underground world deep below the surface. There are many colonies where people live in the underground Labyrinth. The place is known for extreme high temperatures, but also for lodes of gold, silver, and other riches. In one of the colonies named Pin-in, a curious nine-year-old girl named Memempu and her father Gagumber board a two-person work robot and mine for ore. They eke a living as the lowest of lowest "Worker" occupations.

One day, Memempu begs her father Gagumber to set out as Markers — those who chart the innards of the Labyrinth as a spelunker — to search for her mother who left their home. If they encounter a "mysterious giant creature" lurking in the caves, the survival rate is less than 5%. Since discovering an unknown world is dangerous work, "maps" hold great value in the world of Labyrinth and fetch high prices on the market. A Marker is the most dangerous, but also the most lucrative, job. Gagumber decides he cannot hold back the ever-curious Memempu from going off on her own countless times, and finally gives in. The two embark on a journey together in the work robot.

However, the "cost" of curiosity... The "truth" they finally uncovered...

This is a father and daughter's epic journey with the theme of family love.

Source: ANN

Note 1: The runner-up for the "Science-Fiction/Robot" category of the Project Anima.
Note 2: The first episode premiered on Crunchyroll Expo Online on August 5 PT and in Japan on d Anime Store on August 14. Also the first two episodes were streamed on Nico Nico and animelo mix on September 19. Regular broadcast started on October 7.

AniDB | ANN | MAL | TVDB | Wiki (en)