Percatus is a large female colossi mantis that was encountered by Raven as she was traveling to her colossi, Kuromori. She was one of JD's creations whom originally was just a guard. But as time went by she decided to take role of the undertaker. When an intruder, animal, or something else dies, she buries it in her territory. courtesy of Yveltal. During this she even goes as far as to bury the demon king, Trigon, upon request from the spirit council.
She first appears doing her usual job, burying a horn upon request when she finds raven looking in her dug hole. She drops the horn inside and begins talking to her, asking the usual colossi questions and then fighting her, swatting her like a bug with her huge pillar mantis arms. But when she paused for a second, she begins asking about her origin. In the end she shows Raven the grave of her father, Trigon. After a small discussion she actually gives raven her chakra orb to make her feel better, and went on her way.