Curriculum · 3 / 50
Building a hand
An ordinary winning hand occupies four group slots plus a pair; a declared kan still counts as one group despite its fourth tile.
The principle
Almost every winning hand in riichi shares the same structure: four group slots and one pair. Without a kan, you hold thirteen tiles and seek the fourteenth that completes the 4 x 3 + 2 formula. A declared kan contains one extra physical tile but still occupies one group slot. At least one yaku is still required to declare a win.
Rule and example
A group is a run, triplet or declared kan. A run (shuntsu) is three consecutive tiles in one suit, for example 3p 4p 5p. A triplet (koutsu) is three identical tiles, such as 7s 7s 7s, while a kan contains four. The pair (jantou) is two identical tiles. Honor tiles have no runs: they can only form triplets, kan or the pair.
What changes
Two hands break the four-groups-plus-pair mould. Seven pairs (chiitoitsu) needs seven distinct pairs, and thirteen orphans (kokushi musou) collects one of every terminal and honour plus one duplicate. Outside these cases, every hand reduces to assembling four groups and a head.
Mistake to avoid
Mastering this formula reshapes how you read your tiles: each draw is judged by whether it completes a missing group or locks in the pair. It is the foundation of shanten (distance from a ready hand) and ukeire (tiles that move you forward). Without this lens you cling to useless tiles and delay reaching tenpai.
Rules references
- Tenhou rulesReference profile used for game mechanics and scoring.
- WRC Rules 2025International rules compared whenever their options differ from Tenhou.