Adin Elijah is an orphan who has grown up in an orphanage for the past 12 years unaware of what his origins are except for a winged lion medallion he has had since birth. On his thirteenth birthday, he meets an ordinary man (or so he thought) named Artorius, that happens to be a Guardian (the official title of an angel). Artorius reveals to him he is a Nephilim, his mother was a Guardian and his father a mortal. His necklace places him in the well respected Lion-Heart Order where he meets ...