Kaikon (Regret) was the twin peak of Kitai (Hope), among the highest in the Twilight Mountains. The mountains were named by the Crab at the Dawn of the Empire. Miya Akate found them leading a team of Hiruma explorers. The mapmaker made top first in Kitai, but he never returned from his climbing to Kaikon. Both peaks kept the place known as the Lair isolated from the rest of the Empire. Into the side of the mountain was built the Lonely Monastery, and a natural aquifer within the mountain was drained by the Boar to create an underground storeroom known as the Vault.