Nanatsu no Taizai: Mokushiroku no Yonkishi

Percival has spent his entire life with his grandfather atop God's Finger, a remote haven above the clouds, knowing the outside world only through stories that fuel his desire for adventure. His peaceful life ends when a mysterious knight with a shocking connection to his family arrives and kills his grandfather, leaving Percival with one name to pursue and questions he cannot answer alone.

The sheltered boy descends into the wider world for the first time and discovers he barely understands ordinary life among other people. He gathers companions who help him find his way, but also learns that a strange power within him is connected to a prophecy about the Four Knights of the Apocalypse, and that the man he hunts may fear what Percival can become more than what he is now.