Here is the full list of all 31 9 Monkeys of Shaolin achievements.
Complete the prologue mission.
Complete a mission in co-op mode.
Gain more points than another player.
Defeat Shikami.
Defeat Hannya.
Defeat the Kasshiki.
Defeat Okina.
Defeat Fudo.
Finish the game on Warrior difficulty.
Collect all weapons.
Master all styles.
Try every type of tea.
Deflect projectiles 30 times.
Complete a mission without taking any damage.
Finish the game without dying.
The endless cycle of rebirth.
Kill an enemy in the air without touching the ground.
Destroy 30 items by throwing enemies into them.
Parry 50 attacks.
Learn first skill.
Complete all missions.
Revive another player.
Finish the game on Legend difficulty.
Collect all items.
Fully master the first style.
Fully master the second style.
Fully master the third style.
Kill 3 opponents with one strike.
Pull 5 enemies with one seal.
Kill 50 enemies using Qi energy.
Running from difficulties won't solve the problem.