Tetsuzan (斬鉄) is a secret sword technique that normally sets the "blade" as the only concept set inside the blade with a Magic Sequence from Movement Type Magic set to guide the blade's slashing motion. A slash that can smoothly cut deep through thick armor with ease. When Chiba Toshikazu swings his sword enhanced by this magic, his body already knows how to move. Through thousands, tens of thousands, hundreds of thousands of repetitive motions and practice, the slashing action has already been carved into his very body by the time he learned this technique. 
When Ikazuchimaru is used to activate Tetsuzan, not only the blade, but the swordsman is also included within the magic's targets, thus realizing the possibility of high speed attacks and slashes without trembling. This is a technique taken to the logical extreme, once he initiates Lightning Tetsuzan, he can only follow through with the motion. Toshizaku isn't a genius like his younger brother, Chiba Naotsugu, yet he relied on a training regime unknown to other people to earn the ability to use Ikazuchimaru's Tetsuzan technique, Lightning Tetsuzan.