Tsukuyumi Full Moon Down Event Horizon
It is their holy quest to save earth from the Oni. They are mystic warriors, arising from the Jade Kingdom, a realm in which all surviving otherworldly creatures found shelter, after humans began killing and hunting them. The Sentinels still protect the earth whenever Oni walk it. So they return through their jade portals. Possessed with the magic of ancient times, like the Kami had, they can hide in plain sight. Their jade armor hides them, when a mortal is looking at them.