The Mysterious Shrine

Crossing the vast expanse of time, our god shall resurrect on this Earth. When on this altar... a worthy sacrifice is offered.

A mysterious ancient shrine that is located deep underground. It was found by Orochi. According to him, even Psykos isn't aware of this place.

Description
The area near this shrine is flooded with lava. There are several stone pillars and a staircase which leads to a tablet. On this tablet, there is a depiction of a monster bearing a similar appearance to Orochi being given sacrifices by several humans. There is also an ancient text foretelling the resurrection of a God after a worthy sacrifice is given. However, hidden behind the stone is an image of a larger being and the actual "God" the text spoke of.

Background
The shrine was found by Orochi after he began venturing further into deep underground in an attempt to grow stronger by draining energy directly from the deepest parts of the Earth.

When Orochi approached the shrine, he discovered a tablet which depicted him and stated that a worthy sacrifice was needed in order to resurrect God, leading him to believe that it was referring to him as a god. From that point onwards, the Monster King always searched for a "worthy sacrifice" that was required for his resurrection as a god according to the tablet until he met Saitama.

Monster Association Arc
During his encounter with Saitama in the Monster Association Headquarters, Orochi believes that the bald hero is a worthy sacrifice for his resurrection as a god and then leads him to deep underground where the shrine is located.

After being defeated by Saitama who lands a single punch on him that blows his body apart, Orochi's remnants crawl to the shrine as the place begins collapsing. When he is right in front of the tablet, a full image of the actual "God" appears in the mural and is unseen by him.

When Tatsumaki finishes off Orochi with her large spear, the shrine is seen again as Orochi's body is torn apart.

Trivia

 * It is implied that Orochi is actually a worthy sacrifice for the resurrection of God.
 * The sacrificial altar under the mural is adorned with a coiled centipede, possibly hinting at the rise of Sage Centipede from the sacrifice of Orochi.