Using everything
"Y-You're a spirit contractor!?" Gilven was shocked, as he couldn't believe what he was seeing.
A spirit contractor was called to the people who used the power of the spirits. They were powerful and famous in ancient times, but some countries became greedy and wanted to gain their powers for themselves. They launched an attack in various places and hunted those spirits.
Everyone thought that the spirits had gone extinct after that incident. Nobody thought that they were living in the forbidden Dark Forest all along, under the wings of a monster lord.
Souta knew this information because the players managed to access the Dark Forest. Many of the players, including him, across the world venture into the famous Dark Forest. There they found the spirits, deep inside the Dark Forest. At that time, some of the players changed their class into a rare one called Spirit Contractor.