The Shinobi Thieves act as fences and smugglers in the world of Kenshi. They are usually found in bars or residing inside Thief watchtowers within various cities.

You can pay 10,000 cats to join their organization by talking to a Thief Boss standing outside of one of their watchtowers. Joining gives you access to their towers, Assassination Dummies, Locksmith Training Boxes, Beds, Shinobi Traders. Guild Plastic Surgeons, and Wandering Assassins will heal you when nearby. Thieves and Ninja Guards will also aid you in combat.