When Hikari was 5 years old her mother Ichika got lost in the underworld. She was fighting one day with a winged serpent, during that fight, she was badly injured and was almost near her death when some powerful dwarf demon came and chased the winged serpent away. After that day she thought that dwarf demons can be friends with immortals and together they can maintain harmony. One day she thought of going into the underworld and interacting with the dwarf demons and their demon king.  She told her husband Hizashi who was the Emperor of heaven realm, that she wants to go into the underworld. At first, Hizashi refused to let her go. After her continued demanding he agreed but he didn’t want her wife to go alone into the underworld but he also couldn't go with her because he has many duties to perform as an Emperor so he send some troops and some cultivators with her. It was the first time someone tried going into the underworld from heaven realm and some people thought that some kind of tragedy will happen because demons are the creatures of negative energy, they can never live in peace and harmony, it’s in their nature to create chaos.

They were right and she didn’t come back after that day. The troops and the cultivators were found dead and some powerful cultivators were badly injured at the barrier of the underworld that barrier was set by a powerful cultivator. Whenever someone with pure qi goes inside the underworld the demon qi starts to affect their body and that barrier also prevents demons from stepping into heaven. Later people found out that the winged serpent from which Ichika was fighting was the prey of the dwarf demons that’s why they killed the winged serpent, they were not helping her, and Ichika thought that they came to save her.

Those powerful cultivators were found alive but badly injured, their core was crushed by someone, and now for the rest of their lives, they can't cultivate. People thought that it was the demon king, they have only heard of his name that he is some kind of powerful cultivator who ruled the underworld and he is the one who initiated the demonic cultivation. After this tragedy, no one dared go into the underworld. Hizashi send some more troops and people to find out about her wife but later they were also found dead at the barrier. After that incident, no one dared to cross that barrier. Hizashi tried everything to search for his wife but all his efforts were in vain and he couldn't even find her dead body. Hizashi has a daughter whom he loved so dearly, and after her wife’s death, she is the only one close to his heart. When Hikari asked her father about her mother, he told her that she went somewhere for closed-door cultivation and will be back soon. But years passed by she didn't come back and then he told her that she died of qi deviation. Many years later everyone forgot empress Ichika but they still remember that incident and from that onward no one tried again to cross that barrier.