This page in our guide to Devil May Cry 5 is dedicated to Secret Mission 05.
Where to find it: Mission 08 - Demon King
Secret Mission 05
To unlock this mission, use "the lift" and jump towards the platform. Use the Grim Grip points to move to the cave above. There, you will find Red Orbs and the Secret Mission 05.
This Secret Mission can cause you problems. Use Nero's Devil Breaker to move from one Grim Grip point to another without touching the ground. Move to another point when Nero is at the highest point in the air.
Reach the end to receive a Blue Orb Fragment.