Inspired by the original singh rager from 3e D&D Oriental Adventures this is a hengeyokai only barbarian primal path – something unusual in 5e D&D. It emphasis the combat abilities of the hybrid form of the hengeyokai just like the Nine-Tails feat emphasis the combat proves of the animal form. But this is much more of a commitment to the idea than the feat is. This is just a guide, the primal path can be modified to reflect the character of the animal taking the class. This one uses the lion as the base animal.
KOMAINU RAGER – LION
Komainu ragers draw their furious strength from the noble lion (called a singh or singha in some societies). The komainu ragers’ fury never robs them of their discipline and control, which to many minds makes them only more terrifying. They are paragons of warrior virtue whose speed, strength and courage are unrivalled.
From 3rd level when you become a komainu rager, you can release a blood-curdling roar as a bonus action. All enemies within 20 ft radius of you must make a Wisdom saving throw, On a failed save, they are frightened of you for 1 minute. The affected creatures may attempt another save to break the effect at the end of their turn. You may make 1 roar for each Charisma ability bonus you have per day (minimum of 1).
Also at 3rd level, while raging, you may now change into a hybrid form – appearing as a lion-man. You gain the secondary attack of your animal form (for example the lion rager would gain a bite and claw attack). Additionally, each time your proficiency bonus increases you may increase the damage of die of your natural weapons by 1 die to a maximum of d10 – d4 becomes d6, d6 becomes d8, d8 becomes d10.
At 6th level, you become immune to fear. You may also wild shape into a lion once per day for up to 1 hour.
Beginning at 6th level your speed becomes 50 feet (or gain +10 feet to your movement – whichever is higher), your natural attacks are now magical and you gain the keen smell, running leap and pack tactics trait (see the Lion animal entry in the MM).
Starting at 14th level, a komainu rager can act as if under the effects of a haste spell for a total of 1 round per level per day. These rounds need not be consecutive.
SARU RAGER – MONKEY
A modified version using a monkey as a base creature/inspiration.
From 3rd level when you become a komainu rager, you can release an ear-piercing screech as a bonus action. All enemies within 20 ft radius of you must make a Constitution saving throw, or on a failed save, they are deafened and have disadvantage on attack rolls until the end of their next round. On a success, they are only deafened until the end of their next round. You may make 1 roar for each Charisma ability bonus you have per day (minimum of 1).
Also at 3rd level, while raging, you may now change into a hybrid form – appearing as a man-sized monkey. You gain a bite attack that does d4 damage and may be used as a bonus action. Additionally, each time your proficiency bonus increases you may increase the damage of die of your natural weapons by 1 die to a maximum of d10 – d4 becomes d6, d6 becomes d8, d8 becomes d10. At +4 proficiency you may use the bite as a reaction whenever you are hit or missed by a melee attack within 5 feet.
At 6th level, you gain a climb speed equal to your normal speed. You may also wild shape into a monkey once per day for up to 1 hour.
Beginning at 6th level your speed increases by 10 feet and your natural attacks are now magical. In addition, your jump distance is tripled and you have advantage on Dexterity checks. You also don’t take damage from falling 20 feet or less (if not incapacitated).
Beginning at 10th level, you may wield two-handed weapons with one hand. When you use one-handed weapons you can reroll results of 1 on your weapons damage rolls but must accept the reroll.
Also at 10th level, you have advantage on attacks and do +2 damage per 10 feet if you drop at least 20 feet on top of your foe. If you hit you take no damage when you land if you miss you take 1d6 per 10 feet you fell.
From 10th level, you may escape death by receiving a boost of health when reduced to 0 hit points. When reduced to 0 hit points make a DC 10 + half the damage taken Constitution saving throw. If you succeed you back up to 25% of your hit points. Each time this ability is triggered in the same encounter the DC of the saving throw increases by 5.
Starting at 14th level, while raging, your peed is doubled, you gain a +2 bonus to AC, you have advantage on Dexterity saving throws, and you gain an additional action on each of your turns. That action can be used only to take the Attack (one weapon attack only), Dash, Disengage, Hide, or Use an Object action.