Lapis

Lapis is a type of low ranking Oni, which is able to create blue crystals. She watches over her close confidant Spinel, both had become slaves to a mercenary group but, considered useless as their magic could not create stable gems. Because they both had still considerable strength and tactical abilities, they were kept alive and made to do grunt work, as part of the mercenary group. Their captain, was a powerful demon, but considered a tyrant and hated. Uniting, their forces with most of the low ranking demons, and some mid and high ranking once, they began a plan to overpower him. Spinel and Lapis, used a powerful poison, which over time weakened the leader. They waited for him to get drunk, and stabbed him with multiple of their man. Regardless, their captain was too strong and easily shook off this attack. While Lapis suggested a retreat, Spinel instead pushed onward, and almost killed the captain before he used a teleportation spell with a random location, that turned out to be the Human World.