On Mission 15: Diverging Point: Nero, in the area with the first Divinity Statue, there is a path behind it. Following this path will showcase an area where the player is supposed to use the Punch Line in order to reach a Blue Orb Fragment.
After reaching the Blue Orb Fragment, drop down to the right side and walk to the northeast area next to the small Red Orb crystal that can be destroyed.
The goal of this Secret Mission is to simply follow the path to collect the Blue Orb Fragment before the timer runs out. The Speed skill must have been bought from Nico or Divinity Statues in order to complete this. The only real threat in this stage is at the area with the platforms that go down, however Nero can completely skip that area by using a MAX-Act High Roller then a triple jump near the wall, but this can only be done when the game has been beaten at least once.