In 2000 humanity underwent drastic changes when tunnels appeared, humans began awakening and with this awakening The Trials pulled all those who awakened in to learn as quickly as possible how to use there new found energy to defend themselves. Humans adapt quickly and by the end of the first 2 years stability returned with humans in enclosed cities to prevent the evolving creature outside from attacking. But there is no way to stop tunnels from appearing, however tunnels appear less frequently in places with low energy making them safer and therefore more expensive.

As time passed humans learned how to increase awakening chance by having children absorb energy from the cores removed from monsters, all children over the age of five and below the age of fifteen were given free access to cores that matched their potential and were all required to under go combat training from the moment they were capable of running. Because of this humans were able to over the last fifteen years P.T. (Post Tunnels) increase the awakened.

But all is not well as although good energy came through so did negative energy, known as corruption this energy will gather until it blocks ones energy vein intake location meaning those born with less corruption and bigger intake locations the higher the talent and the longer they can cultivate. All children when they turn fifteen will immediately be drawn in to The Trials as all children under 10 years old when the Tunnels appeared are guaranteed to awaken but the longer they go before cultivating the more their intake locations will shrink. However in dungeons corruption is higher and some can get into energy veins until it blocks them cause the energy in them to pile up until they implode, a unique medicine was made to combat this problem but it can only flush so much and if not careful it is easy for hunters to overwhelm and end up imploding. 

A society of guilds rose to make regulations for who could be hunters and therefore enter the tunnels and close them to prevent invaders. 10 years after the tunnels appear being a hunter became a sought after and lucrative job, but only those with D-grade or higher energy veins and certified as capable fighters could be hunters and the tunnels people could enter was regulated based off strength. The current percentile for vein energy is 15% F-grade, 35% E-grade, 20% D-grade, 15% C-grade, 5% b-grade, 1% A-grade, 1% divided between s, ss, sss grade veins, and the last remaining 8% for those with malformed veins that can't hold energy. This is the way society has been shaped and ones chance to change your fate are bound by your ability at birth.