Yotsudama gives you touch, thin-hit awareness and close-position control. Three-cushion asks you to keep those assets while replacing the scoring picture: one fewer ball, an explicit three-cushion route and a much narrower arrival window.
Start with the current rules, not club folklore
The Japan Billiards Association’s revised carom rules take effect on 1 January 2026. They specify white, yellow and two red balls for four-ball play. The general scoring definition awards one point when the cue ball contacts two other balls; the four-ball chapter also manages repeated scoring inside marked restricted areas.
The same official rules define three-cushion with three balls and require at least three cushion contacts before the cue ball reaches the second object ball. The NBA describes three-cushion as today’s mainstream carom discipline in Japan, while the national four-ball championship belongs mainly to amateur competition after its broad popularity in the Shōwa 30s and 40s.
Use local names carefully
In Japanese, use 四つ玉 (common spelling) and 四ッ球 (the spelling seen in official championship naming), with yotsudama as the reading aid. Korean 4구 (사구) names a related four-ball tradition, but club handicaps and detailed rules must not be assumed identical to Japan’s rulebook. In this guide, Turkish dört top karambolü, Vietnamese bida 4 bi, Dutch vierbal, French carambole à quatre billes, Spanish carambola a cuatro bolas, German Vierball-Karambolage and Italian carambola a quattro bilie are descriptive equivalents, not claims of one worldwide ruleset.
What changes when the fourth ball leaves
The broader libre-to-three-cushion guide already covers transferable stroke and aiming fundamentals. Yotsudama adds a different problem: a familiar extra scoring object disappears, so gathering balls is no longer the objective and the route must be planned before contact.
- Remove one red: do not mentally keep it as an imaginary rescue ball.
- Declare the first object ball, cushion one, cushion two, cushion three and only then the second object ball.
- Judge success by the cue ball’s arrival window, not by whether it passed near both balls.
- Separate yotsudama points, 持ち点 and three-cushion average in your notebook; none is an automatic conversion of another.
Four drills that do not repeat a generic libre course
These drills target the four-ball-specific reset rather than reteaching stance or centre-ball contact.
- Fourth-ball removal audit: build a familiar four-ball cluster, remove the spare red, and name a legal three-cushion route before every stroke. Ten positions, no shot until the route is spoken.
- C1–C2–C3 ladder: point to each intended rail in order. A contact with both object balls before the third rail is a failed route even when it would have scored in four-ball.
- Second-ball window: choose a hand-width visual window beside the second object ball. Keep the balls fixed for ten attempts and change only speed; then repeat with side spin. Do not place chalk or markers on the cloth.
- Two-ledger session: record four-ball performance and three-cushion caroms per inning in separate columns. Compare trends within each discipline, never by a made-up multiplier.
Why 持ち点 is not a conversion formula
Japanese events may ask entrants for 持ち点 and then set an event-specific match distance. For example, the JPBF’s 2026 Emerald Cup entry page asks for 持ち点 while publishing a five-point match format. That is evidence of event administration, not a nationwide average-to-handicap table.
Use the average calculator to record three-cushion points divided by innings. It deliberately does not manufacture a yotsudama, 4구 or 持ち点 conversion where no current official nationwide mapping was verified.
A focused 30-minute bridge session
Minutes 0–5: five fourth-ball-removal audits without shooting. Minutes 5–15: ten C1–C2–C3 ladder attempts. Minutes 15–25: ten second-ball-window attempts with one-variable changes. Minutes 25–30: enter caroms and innings, then write one route error and one speed error for the next session.
If you need general libre transfer fundamentals, use the existing guide linked below. If this yotsudama-specific session exposes weak cushion counting, stay with the ladder instead of adding more systems.
Open the three-cushion table
Set your own three-ball position in the simulator, say C1–C2–C3 before shooting and log only valid three-cushion caroms.
Open simulator →Record three-cushion average · Read the general libre transition guide