Saku Tatsuhiko

Saku Tatsuhiko (佐久 辰彦) age 28 is the leader of BLOCK

He is a big man who is constantly described as "bear like", he displays a serious no nonsense personality and leads BLOCK's revolt through a series of complicated plans and strategies meant to fool Academy City's higer ups, his plans included large diversion tactics involving SCHOOL and GROUP and using 5000 hired mercenaries. He seems to be fond of ruthless tactics, a fact that would eventually end up with him being taken out by Teshio Megumi, another member of BLOCK.

The goal of his revolt is being able to escape from the Academy City's world, where everything is under Aleister's Grip, the first set back of his plan would be when Etzali used an indirect method to alert Academy City's defense system and the unmanned helicopters known as six wings and the 5000 mercenaries he hired where almost entirely wiped out. The second setback to his plans was getting involved with GROUP when they trying to squeeze out Move Point's identity, at that point is when Teshio grew tired of his methods and sent him to sleep with a fist in the face.

He wasn't killed, he was just knocked unconscious; considering the situation on which he was taken out is quite likely that he was apprehended afterwards. He seemed to have a close relationship with Teshio Megumi