Here is the full list of all 14 Manaya achievements.
Finish Level 1.
Finish Level 2.
Finish Level 3.
Finish Level 4.
Finish Level 5.
Get Grade S.
Get Grade A.
Get Grade B.
Get Grade C.
Get Grade D.
Defeat The Final Boss.
Defeat The Final Boss 3 Times.
Defeat The Final Boss 5 Times.
Defeat The Final Boss 10 Times.