Saraku

Saraku is a Level 4 operative of MEMBER. His ability is Kill Point (死角移動). He can teleport behind his opponent, but cannot calculate the theoretical value of the 11th dimension, so he needs to know the current location of his opponent in order to activate his ability. He was apparently killed after trying to delay Accelerator who was on a mission for GROUP, however later the Professor disclosed that they should recover him since he is still alive. His ability isn't originally called Kill Point, but it's a name that the Accelerator gave it since Saraku couldn't teleport using calculations about the 11th dimension, the Professor seemed fond of the name.

Trivia
It is unknown if his power level is actually 4. The Accelerator noted that being able to teleport your own body already qualifies as level 4, however with the impairment of not being able to calculate the 11th dimension, the Accelerator pointed out that a failure like him can't be good enough to be a level 4.