Santōryū

You wield three swords. One in each hand and one in your mouth. It takes years of dedication to master. Wield three blades simultaneously, weaving through foes with unmatched precision and finesse.

Three Sword Style

You now have the ability to wield three swords. One in your mouth, and one in each hand. Due to your now restricted movement, you are no longer proficient with medium or heavy armor.

When you roll initiative, you can draw your three swords without taking an action. To do so, you must have two hands - and one mouth - free. The swords can't have the heavy or two-handed property.

While triple-wielding, you can engage in Three-Weapon Fighting. When you take the Attack Action and Attack with a sword that you’re holding in one hand, you can make a single attack with a different sword that you’re holding in the other hand as part of that same action, and use a bonus action to attack with your third sword in your mouth. 

Swordsman's Shame

Opponents do not gain advantage when you're engaged and they are behind you.

Double-Edged Blade

You can use your reaction once per long rest you can turn a Critical Fail into a Critical Success, but you take half of the damage you deal to your opponent. (only with weapons that deal slashing damage)

Gorilla Techniques

You drastically increase your strength for attacks adding 1d12 to your attack

Higher levels: 
     Level 13: 3d6 
     Level 16: 3d8
     Level 18: 3d10

Nothing happened... nothing at all

When knocked out, you make a CON save with a DC of 5 + (damage left over from enemy attack). If you succeed, your health is raised to 1 hit point

EX: You have 30 health. Someone hits you for 40 damage. You are knocked out and need to make a CON save with a DC of 5 + the leftover damage (10). If you succeed, then your health goes to 1 instead of 0.

Higher Levels: 

    Level 16: Can use this ability twice per long rest
    Level 18: You come back with 5 hit points
    Level 19: You come back with 10 hit points and the DC changes to only the left over damage. No 5 + left over damage

Asura

You summon the power of the demon, Asura, to help you in your fight. Because of this you grow an extra 4 arms, allowing for you to attack 4 more times in your action. You CAN use action surge on this, and it lasts until the end of your next turn. (2 turns total)