Here is the full list of all 17 Twin Stones: The Journey of Bukka achievements.
Kill your first enemy.
Complete Level 1
Get together with Shiva
Complete Level 2
Complete level 3
Complete level 4
Complete level 5 and finish the game
Kill two enemies with the same attack
Obtain S in a level
Obtain S in all the levels
Complete the tutorial before 3:00
Complete the level 2 before 8:00
Complete the level 3 before 7:00
Complete the level 4 before 9:00
Complete the level 5 before 4:00
Complete all the levels in the required time
Complete a secret area