The Seidan Guard is Orderrealm's law enforcement. They maintain order, and punish those who violate the law or cause disorder in the realm.
The Seidan Guard also invades other realms to bring order. The Outworld city of Lei Chen was taken over by Hotaru in the name of Order after the Seidan Guard helped drive out the invading Tarkatan forces. The Seidan Guard has also frequently invaded Chaosrealm to gain control of it's water supply.
