Sponichi is calling Yu Darvish's new pitch the Gyro-cutter. According to a number of reports, the pitch is apparently a rising cutter. According to Motohiro Shima (he caught Darvish last night), the pitch rises up above the letters towards left-handed batters and sinks away from right-handed batters.
Norichika Aoki told reporters that he thought the pitch rose. Alex Ramirez didn't notice anything special and figured it was just a fastball. And Hayato Sakamoto said he thought he saw cutter-like movement on the pitch.
The Sponichi articles goes on to list all 13 of Darvish's pitches: fastball, slider with vertical movement, slider with horizontal movement, 120km/h range fast curve, 110km/h range curve with vertical movement, 100km/h range big breaking curve, 140km/h fast change, 130km/h change, fork, two-seamer, one-seamer, sinker, cutter, and now the gyro-cutter.