Yoroitoshi

"Get ready! Yoroii...toshi! (覚悟して！ 鎧ー…通し！)"

- Ibuki

The Yoroitoshi (鎧通し), also written as Yoroi-Doushi, is one of Ibuki's special attacks, introduced as her second Super Art in the Street Fighter III series and first Ultra Combo in Super Street Fighter IV. This move is Ibuki's only projectile (if the grab was unsuccessful).

Street Fighter III
Executed by performing two quarter-circle forward ? motions and pressing punch, Ibuki manipulates a massive amount of ki, and performs an extra-powerful, unblockable Raida attack on the opponent's torso. If it fails to grab the opponent (e.g. too far away), she extends her arm and fires an orange colored blast that moves about four inches and gets smaller.

Super Street Fighter IV
Executed by performing two backward-half circle motions and pressing all 3 punch buttons, Ibuki performs a Raida; if it connects, she performs a more powerful one using her elbow, instead of her fist.

Street Fighter X Tekken
The above variant is used in Street Fighter X Tekken, where it requires only one half-circle motion; the whiff projectile travels the length of the screen.

Etymology
Yoroitoshi roughly translates to "Armor Piercer" in English, as shown above, which may refer to the move's unblockable nature. It is also the name of a Japanese dagger-like sword used for just that purpose.