If you get all S ranks on every mission, you will unlock the All Star Group Photo.

In addition to earning points for Time and enemies killed, you will earn bonus points for completing the game's secret missions. Point values are listed below:

Critical Hit: 200
Phantom Baby: 100
Phantom Baby 2: 100
The Three Beasts: 100
One-Eyed Evil: 200
Wandering Ghost: 200
Water Cell: 100
Treasure of the Reaper: 200
Stairway of Tranquility: 100
Shadow of Darkness: 200
Blue Gem in the Sky: 200
Hidden Bangle: 200

S: 1000-1500
A: 800-999
B: 500-799
C: 0-499
D: -1 or below

Critical Hit--Mission 3
Drop into the water near the broken bridge.

Phantom Baby--Mission 4
Go back into the church where you battled the Phantom.

Phantom Baby 2--Mission 4
Defeat Phamtom Baby, then go to the God of Time room.

The Three Beasts--Mission 4
Inside room under the biplane room.

One-Eyed Evil--Mission 5
Go back to the room where you first saw Beezelbub.

Wandering Ghost--Mission 11
Go back to the final room of Mission 10.

Water Cell--Mission 13
Go to the captain's skeleton in his room.

Treasure of the Reaper--Mission 15
Look at the skull in the room where you first got the Shield Emblem.

Stairway of Tranquility--Mission 16
Beat Griffon, then go back to the coliseum.

Shadow of Darkness--Mission 16
Beat Nightmare, then return to the biplane room again.

Blue Gem in the Sky--Mission 17
Use Air Raid to cross the broken bridge.

Hidden Bangle--Mission 21
Look at the wall in front of the God of Time statue.

Durng gameplay, press R3 to quickly switch between Ifrit and Alastor modes.