The White Brows Association was a group of assassins active in the Capital of the Empire.
The Association was composed of elderly men who couldn't find a place for themselves after retiring and could only find joy in killing others. They formed a mercenary group which would take any request they could, including the assassinations of women and children, in order to satisfy their bloodlust.
All of its members were exceptionally skilled in Iaidō: the art of drawing the sword, slicing the opponent and sheathing it in a blink of an eye. With it, they were able to kill their targets before they could notice anything, only dying a few seconds later. They wore clothing associated with samurai and ninja; all of them had grey hair, presumably an inspiration for the group's name.
The group was traveling across the Empire before finally returning to the Capital and settling down in a mountain temple. After killing a large group of people in the Capital's main street, the Association became a target for Night Raid. Night Raid members faced the four elderly men in battles and were able to kill them.
- Gensei (†) was Bulat's sensei and previous holder of Incursio. He was killed by Bulat after Night Raid targeted him for assassination.
- A tall, muscular man with a grey three-point beard and spiky hair on the sides of his head. He wore no shirt and loose fitting short pants, he also had bandages around his legs and forearms. He wielded a black broadsword and a small blade in combat. He was attacked by Leone while meditating under a waterfall. She managed to break his sword, but he was quick enough to fight back; however, Tatsumi ambushed him and killed him after a brief fight. While not showing much personality, the elderly man seemed to have great pride in his age and ability and expressed disbelief when the two "brats" turned out to be strong enough to beat him.
- A lean-built man with grey, spiky hair who wore a bodysuit similar to a ninja outfit as popularly depicted, along with a scarf. He also wore bandages around his forearms and legs. He wielded a standard katana. He fought Sheele who distracted him with Extase's flash of light and called her a weak little girl, before he was shot by Mine in the chest, killing him. He seemed to have been quite aggressive and arrogant and insulted the Night Raid members before he died.
- A man with long grey hair on the back of his head and long eyebrows. He wore a samurai outfit similar to Gensei's. He faced Akame on the bridge and was killed by her very quickly. He carried an unusually long katana. He seemed to have a calm and collected personality and compared people bleeding to red flowers blooming, which he considered to be the "ultimate beauty". Even while dying, he remained true to this, claiming that the red flowers were truly the most beautiful.