The Crimson Lotus is a criminal organization that once spanned the entire countryside of the main continent. They were mainly based in the Land of Fire and engaged in a long war with Konohagakure. Their leader was Shuriyko Uchiha, a man of great renown, and the direct descendent of Sasuke Uchiha himself. He amassed a large collection of loyal followers who were more than willing to sacrifice their lives for the cause. Their motivation and Shuriyko's goals were unknown, and even after their defeat remain clouded in mystery.
While active they were incredibly destructive, yet did not have any connections to the other criminal organizations. Even so, they were the largest out of them all and had amassed well over ten thousand verified casualties. The Red Fortress is where they resided, a stronghold at the very south edge of the Land of Fire. No one who entered the vicinity ever returned. The land there used to be a great coast with thick forests, but now it is barren and grey.
The organization was made up most of lowly thugs, these men scour the landscape, razing land and working as scouts. The army was made up of mostly missing-nin that have joined his cause, fighting on the front line against Konoha. Shuriyko had more than just lowly ruffians and missing-nin on his side however. He had a council of very power individuals that serve as his generals. These men were all extremely powerful.
Recently the Crimson Lotus attacked in unison with an army of Sound-nin and were able to conquer Konoha. They repurposed the city as their new criminal stronghold from which the continued to spread their terror. After holding the city for some time, the Konoha-nin were able to organize and gather enough support to take back Konoha, wiping out the Crimson Lotus forces and killing Shuriyko.