Can secret will-sapping gas through his body
Shirow Ishihara was a part of the Tokyo Thieves Guild along with his older sister Zoe. But the scientists involved planned on using him as a mutant cow, gathering the gas he secreted to sell on the black market.
He was rescued by Zoe. They were for this excommunicated from the Guild. They two then became members of the New Orleans Thieves Guild. They sought refuge from the international slave trader, the Pig, who sought to capture Shirow and use the gas to take over the world. Along with Gambit, the Ishihara's were captured by the Pig's agents.
They escaped with Shirow. Under the influence of Shirow's gases Gambit ordered Pig to walk off a cliff.
It is unknown if Shirow Ishihara lost his mutant powers after the M-Day.