The Yomotsu Hirasaka (黄泉比良坂 Yomotsuhirasaka), Yomotsu Hills, Hades Slope or Underworld Hills is the most superficial part of the Meikai. It consists of a series of hills ending in a steep precipice and a seemingly bottomless hole, which leads directly into the Underworld (Meikai).
This is the place where dead persons' souls wanders, marching in line to fall into the hole. It is said that if a soul falls into the abyss, there is no way of coming back.
It appears not to be a place created or dominated by Hades (therefore not part of the Meikai, but a doorway to it), as a live person does not need the Eighth Sense to travel here, only a special technique called "Seki Shiki Meikai Ha" is needed.
In the original series, during the battle of the Twelve Temples, Cancer Deathmask lured Dragon Shiryu there with his "Seki Shiki Meikai Ha", albeit the Dragon was able to overpower the Gold Saint and throw him into the hole.
In the Hades arc, Wyvern Rhadamanthys used his own "Seki Shiki" to lure the resurrected Deathmask and Aphrodite to Yomotsu to punish them for their failure in killing Athena, throwing both of them into the hole.
Virgo Shaka used an illusion to make the resurrected Aquarius Camus, Capricorn Shura and Gemini Saga believe they were in Yomotsu when they crossed Cancer Temple. It was so real that they were even attacked by corpses, until Saga figured it was an illusion.
In The Lost Canvas, Yomotsu appears to be controlled by Hades, as it has skeleton guards dwelling in it (Markino is one of them), and even guiding the dead's souls in line into the hole.
It also has a small building with a torture chamber and prison. Here was where Mandrake Fedor held captive Tenma's soul, until Yato and Yuzuriha came to rescue him (sent by Hakurei using his own "Seki Shiki Meikai Ha"). It must be noted that there is an exit of this builiding that also leads to the Meikai.
It is also the scenario of the battle between Cancer Manigoldo and Nasu Veronica. Manigoldo used his "Seki Shiki Meikai Ha" to lure Veronica to Yomotsu. The Nasu Specter referred at this place as "a playground" for Specters.
It also must be noted that in the original series, there is another doorway to the Meikai at Hades' Heinstein Castle.