The following page of our guide to Devil May Cry 5 contains a description of the tenth secret mission in the game.
Secret mission 10
Where to find it: Mission 14 - Crossroads: V
Secret mission 10 is hidden almost at the very end of the mission. Once V gets all powers back. Run to the blood clot and destroy it - right next to it, the secret mission will appear.
Your mission is to reach the blue fragment of the orb without touching the ground. To do this, make a leap towards the Crystal, wait until you get a bit lower (so as to be able to fly through the niche) and soar with the help of the Griffon. When you start falling, use V's finishing attack, to teleport a bit further. You should reach the Crystal easily.