Fastball
Razor Shuuto
Think of it as the shuuto with a sharper edge — Hiramatsu's famous pitch jammed righties so hard and broke so late that people said it looked like it cut the air instead of tumbling.
The grip
Hold it like a two-seam fastball and finish with hard inward wrist-and-forearm rotation, snapping the wrist tighter than a stock shuuto to spin the ball harder to the arm side.
Grip paraphrased from Wikipedia's shuuto entry (two-seam-style grip plus inward pronation); the "tighter snap" framing is the descriptive distinction that earns the razor variant its name, not a measured spec.
What it does
It runs hard down-and-in on a right-handed hitter with a sharp, late arm-side cut — the break that reads as slicing through the air rather than tumbling, which is what set Hiramatsu's version apart.
Direction and the "cuts the air" sharpness are paraphrased from Wikipedia's shuuto entry. Hiramatsu pitched decades before radar/Statcast, so the shape is described in words only, never as a measured number.
What it really is
A named, sharper-breaking variant of the shuuto already in the atlas — same down-and-in arm-side family, distinguished by its harder, more knife-like late break; it is not a separate pitch type from the shuuto.
Who throws itMasaji Hiramatsu (Taiyo Whales, 1967-1984), the definitive practitioner — his version earned the "razor" nickname; he reached the Japanese Baseball Hall of Fame.
Study this first
Catchers who handled the shuuto called it a two-seamer, and the razor is that same arm-side family with a sharper, later break. The filed Two-Seam is where to learn the grip underneath it.
Basic file
This pitch has a sourced one-line grip and movement and an honest explanation, not yet a filed specimen with authored grip geometry and a full craft chapter. A fuller breakdown is coming. Sourced, not corrected.
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