Saku Tatsuhiko leads BLOCK, a faction operating in Academy City's underworld. He's best known for orchestrating an ambitious but ultimately failed coup attempt on October 9, when he marshaled around 5,000 external mercenaries with the goal of striking at Aleister Crowley and seizing control of the Dark Side. The whole operation fell apart thanks to GROUP's intervention. He's a minor character in Toaru Majutsu no Index, but fans often remember him as the face of one of the series' more memorable power plays against Academy City's establishment.
Content compiled by AnimeList.moe from publicly available sources.
