Ryoko's Guide to the Yokai Realms, pg 218
Prerequisite: Proficiency with kusarigama
You have mastered the use of the kusarigama, learning additional techniques to trip and harass your foes. You add your ability modifier to the damage roll made with a kusarigama’s counterweight. In addition, when you make this attack against a Medium or smaller target, you can choose to deal no damage. If you do, the target makes a Strength (Athletics) or Dexterity (Acrobatics) check (target’s choice), contested by your attack roll. If it fails the contest, choose one of the following effects:
• The target is disarmed of one object it is holding of your choice, which is pulled towards you and falls at your feet.
• The target is knocked prone.
• The target is pulled 5 feet towards you. If that leaves it within your reach, it is grappled by you. While a creature is grappled in this way, you can’t make attacks using the kusarigama’s counterweight.