How about an idea for a monk? Always fun to learn new folklore!

Monk-Student of Ōya no Tarō Mitsukuni 

Monks that follow Ōya no Tarō Mitsukuni follow this samurai due to his battle prowess and ability to overcome the impossible.  Having heard tales of this man kill the unkillable giant skeletons sent against him by a practitioner of black magic, you now learn at the feat of the master as he reveals his secrets to you.  He is a warrior first and an honorable competent second, but you find it hard to belittle the man for his results.  You now learn to combine his techniques with your monastic training to survive the unsurvivable.

Path of the Sword

Starting when you choose this tradition at 3rd level, you learn how to use a longsword/katana.  This weapon counts as a monk weapon for your flurry of blows.  When you increase your unarmed damage, increase your longsword damage as well.

Level	Damage
3	1d8
5	1d10
11	1d12
17	2d8

Learning From Your Foe

At 6th level you learn how the masters sneak into the enemy’s home and even their very bed to learn the secrets of its attack.  You gain proficiency in Deception and Stealth skills.  If you are already proficient in either of these skills, gain a +2 bonus to that skill instead.

Mastery of Onmyōdō

Beginning at 11th level,  the master reveals the magics of life and death to you and how to survive the magic assaults on your life.   When you are attacked by a magic attack or effect, you can spend a ki point to gain advantage on the saving throw.

Against the Impossible

At 17th level you no longer need the master to teach you how to do what must be done, you have learned to master the impossible.  When you would be reduced to zero hit points, you can spend 3 or all your remaining ki points (whichever is less) to avoid the attack and gain hit points up to your maximum.  You can only do this once and then you must complete a long rest before you can use this feature again.

Thoughts?

I’ve been known to fly into a crazy rage and I’ve got a black belt. Let’s get some peanut butter into the chocolate!

The Way of Anger

Not all monks practice the art of silent meditation and delicate self-discipline. Some monks fuel their abilities on the anger that burns in their soul. These monks learn to harness that anger and release it at their enemies when the time arises.

The Way of Rage

Starting when you choose this tradition at 3rd level, you learn to harness your anger to move faster and hit harder. You enter a fugue state where only combat matters as a bonus action on your turn akin to a barbarian’s rage. You gain the following benefits

• You have advantage on Dexterity checks and Dexterity saving throws.
• When you use a bonus action to make an attack, you may make an additional unarmed attack. This stacks with bonus action attacks from ki point use.
• Melee attacks against you are made at disadvantage.

If you are able to cast spells, you can’t cast them or concentrate on them while in this state.

Your rage lasts for 1 minute. It ends early if you are knocked unconscious or if your turn ends and you haven’t attacked a hostile creature since your last turn or taken damage since then. You can also end your rage on your turn as a bonus action.

You can do this a number of times per day equal to your level /3 + 1, minimum 2 per day. Once you have raged this number of times, you must finish a long rest before you can rage again.

Any effect, ability, or feat that would affect a barbarians rage also affect this ability as well.

All Out Attack

At 6th level, your training in focusing for combat bleeds into your ferocity during your rage. If you declare one target as the soul person you will attack this round at the start of your turn, you gain two ki points that you must spend this round in attacks against this target or in advancing on the target. If the target dies or is incapacitated during your round, you may not attack another target but may continue to attack the target’s body or remains.

Hatred

Beginning at 11th level, you now enter a state where you no longer experience the outside world during your rage state. During your rage, you gain resistance to psychic damage and have advantage on all Intelligence, Wisdom, and Charisma saving throws.

Only Violence

At 17th level, you gain the ability to literally let rage keep you alive. If you would be knocked out or killed while in a rage, you are allowed to stay conscious while making death saving throws. Increase the number of death saving throws you are allowed to make before dying by 3 while in a rage. Each round you automatically fail your death saving throw if you stay conscious in a rage. Critical hits on you increase the number of failed death saving throws you have failed by 2. While using this ability, you can not be healed or regain hit points. Each round you gain a number of ki points equal to your number of death saving throws you have currently failed. These addition ki point occur after abilities like perfect self have increased your ki pool. As a free action, you can voluntarily end your rage at the start of your turn and fall unconscious and stabilized at 2 death saving throws failed.

Thoughts?