Orochi Oniwabanshu

The Orochi Oniwabanshu are a squad of ninjas who directly serve Kurozumi Orochi, the shogun of Wano Country. Their captain is Fukurokuju.

Overview
Operating in secret, the Orochi Oniwabanshu defends Orochi from any potential threats. Being ninjas, they know ninjutsu and are capable of moving around in secret to catch intruders by surprise.

Wano Country Arc
The Orochi Oniwabanshu spotted Nico Robin sneaking around Orochi Castle and caught her by surprise inside one of its rooms. The captain Fukurokuju then came in and gave Robin a chance to explain herself.

Trivia

 * The Orochi Oniwabanshu are likely based on the Oniwaban, a group of undercover security guards employed by the Japanese shogun in the feudal era.