Look around - you should find secret mission 08 and Red Orb statue. Inside a trunk you can also find Vital Star M (jump up into the hole).
Secret Mission 08: Royal Blocker
Perform Royal Block 5 times.
Tactics: You have to do it with Dante, not Nero.
Before you go down into the valley, go along the cliff and take Holy Water. Destroy Chimeras and go east.
Ruined Church/Ruined Valley
Destroy Chimeras, break the glass and eggs behind. Go upstairs, activate the machine and go over the disappearing bridge trying not to fall. You can shoot Mephistos with Charged Shot. There is a Blue Orb Fragment above the bridge - take it using Air Hike.
It's safe here, go to the other side of the river, on the left you will find Secret Mission 05.
Secret Mission 05: Sky Scraper
Reach the top of the shaft under one minute.
Tactics: Launch yourself up using first red platform, then use a Grim Grip, now fall onto the second platform, turn yourself toward the middle of the shaft, use Grim Grip and jump onto the third platform. Fourth platform is protected with fence - jump up, destroy a fence. From the fourth platform jump directly to the platform near wall. Land on it, find the last Grim Grip, use it to reach fifth red platform.
Ancient Plaza/Windswept Valley
Pass through Ancient Plaza destroying Chimeras on your way.
In Windswept Valley activate Gyro Blades and destroy barriers and Chimeras till you reach the gate.
Ruined Valley/Forgotten Ruins
Run over the bridge destroying eggs. Before you leave to fight Echidna, use a Combat Adjudicator (you have to reach "atomic" status to destroy it).
Echidna isn't easy to destroy so take a Vital Star just in case. When you're able to attack her true self, use Devil Trigger. When she's flying around shoot her with Charged Shot. Stay close to her using Snatch and attack nonstop.