Soul Crystals are the secret to the Raitoejji's ability to emit a blade made of pure natural energy. Soul Crystals are created when a lot of natural energy is directed to a tiny spot inside The Cave of Legend. This gives it the natural ability to draw natural energy to it. Usually Sage's can bite it to to enter Sage Mode quickly. However, Haru's mother's side of the family discovered a different use for this crystal.