Riichi Mahjong Trainer

Yakuman. A hand composed entirely of honor tiles — winds and dragons only. Often built around a chiitoitsu shape because honors form pairs more easily than triplets. Stacks with honroutou and (sometimes) shousangen for double yakuman in stricter rulesets.

Every tile is a terminal (1 or 9) or honor. 2 han. Since terminals and honors cannot form sequences, the hand always pairs with toitoi or chiitoitsu — the resulting stack is typically 4 han or more before dora.

Winning by ron on the very last discard of the round. Companion to haitei (the equivalent last-tile self-draw). Easy to overlook — always recheck waits as the wall empties.

Yakuman. Four concealed triplets in a closed hand. The fourth triplet must complete by tsumo to keep all four concealed — a ron win with a shanpon wait counts the winning triplet as open and downgrades the result to san ankou + toitoi instead.

Sequences 1-2-3, 4-5-6 and 7-8-9 all in a single suit. 2 han closed, 1 han open. The same-suit cousin to sanshoku-doujun — vertical inside one suit versus sanshoku's horizontal three-suit spread, and the two cannot coexist.

Winning within one go-around after declaring riichi, before any call or kan interrupts the turn. Closed-only by virtue of requiring riichi, and one of the cheapest ways to add a free han to a riichi hand — it stacks freely with everything else riichi unlocks.