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Riichi or damaten
Riichi adds a yaku and enables ippatsu and uradora, but reveals and constrains the hand; damaten keeps tenpai hidden and flexible without those bonuses.
The principle
Declaring riichi adds one han, enables ippatsu and unlocks uradora. It also makes the declaration visible, places a 1,000-point deposit and normally forces every new draw to be discarded. Under Tenhou, an ankan using the drawn tile remains possible if the wait does not change, even when structure or yaku changes. WRC 2025 also requires the structure to remain unchanged.
Rule and example
Damaten means keeping a closed tenpai without declaring. Ron is legal only if the hand already has another yaku; otherwise only a shape change, closed-hand tsumo or riichi declaration can provide the right to win. Damaten preserves the ability to change waits and defend.
What changes
The choice depends on secured value, wait quality, remaining tiles, score and danger. There is no absolute answer: an exact comparison must state these variables and the payments needed for the target placement.
Rules references
- Tenhou rulesReference profile used for game mechanics and scoring.
- WRC Rules 2025International rules compared whenever their options differ from Tenhou.