What remains here is only the pitiful result of wanting to take back one's own regrets.

Several years after the end of the war between humans and fairies, while the capital has recovered splendidly, many districts are still in the midst of recovering from the war.
As part of his training, Martin, a young man studying to become a clergy, is traveling from town to town in order to deliver assistance, his friend and companion Chloe in tow.
One day, circumstances brought 'their journey' to an abrupt end.

When they awoke, they were in a cold underground world, as dark as the night.
According to Hugo, a fairy they met there, they were in an alternate dimension known as Rimbus, and the only way to return to the surface was to wait for a large door to open, which only does so on its own accord.

"If you're lucky, you might make it out pretty soon, but if you're not, it may never open in your lifetime.
And once that door is open, 'only one person' can leave."

Martin was at a loss, but in contrast the corners of Chloe's mouth slowly lifted up.
It was a dark and twisted smile that somewhat seemed happy.

[Translated from the official website]