One of the five convicts, from Russia.

He is inhumanly strong, was able to climb an almost entirely smooth wall for 100 meters. Sikorsky is very fast. When Baki Hanma knocked Sikorsky out of the hotel, he was able to climb up in a few minutes. He could grab and hold to a fire-extinguish with two finger for a long period of time. Using his finger strength, he can cut through a persons flesh using only his knuckles. Sikorsky nearly killed Alexander Gallen in a fight.

(Source: Baki Wiki)