Rokushiki/Tekkai

Tekkai is one of the six techniques of Rokushiki.

Overview
The   Tekkai  (鉄塊 Tekkai?, literally meaning "Iron Mass" or "Iron Body")   hardens the users' muscles to the level of iron, in order to nullify damage taken from attacks. However, it can be broken by strong enough forces.

When Tekkai is active, the user is unable to move. Tekkai can also be used to enhance the users attacks by the increased density one gets from using Tekkai.

The strength of Tekkai can vary for users with different physical conditions, as a person with a higher level of muscular strength would be able to take stronger forces and enhance attacks with his/her use of Tekkai. Furthermore, despite the increased physical density that one gains when activating this move, one should remember that the user's body is still flesh and blood. Thus, its resistance to other than solid attacks remain pretty much the same, making the user as vulnerable as ever to certain attacks. As such, even masters of Tekkai are far from indestructible.

Variations of Tekkai

 * Tekkai Kenpo (鉄塊拳法 Tekkai Kenpō?, literally meaning "Iron Mass Style"): Used by Rosa Malik here Using Tekkai Kenpo, the user is able to move while using Tekkai.
 * ​Tekkai Kenpo "Don Poro" (鉄塊拳法「重歩狼」 Tekkai Kenpō "Don Pōrō"?, literally meaning "Iron Mass Style: 'Important Wolf Step'"): A punch to the opponent's stomach with Tekkai in use.
 * ​Tekkai Kenpo "Matenro"(鉄塊拳法「摩天狼」 Tekkai Kenpō "Matenrō"?, literally meaning "Iron Mass Style: 'Devil-Heaven Wolf'"): The user hardens their foot, possibly their whole leg, with Tekkai and drops down on their opponent.
 * Tekkai Kenpo "Shooting Star": The user hardens their hand, possibly their whole arm, with Tekkai and strikes the opponent from above.
 * Max no Tekkai: Used by Rosa Malik. Rosa maxes out his Tekkai making it harder than a normal Tekkai.