Tsuuiisou

Tsuuiisou

Tsuuiisou (字一色, つーいーそう) is a yakuman where your entire 14-tile hand consists solely of honor tiles—winds (East, South, West, North) and dragons (White, Green, Red). No suited tiles (characters, bamboo, dots) are allowed. The name translates to “all honors” or “all character tiles.”

Detailed Explanation

Requirements

To achieve tsuuiisou, all 14 tiles must be honor tiles:

• Wind tiles: East, South, West, and/or North
• Dragon tiles: White (haku), Green (hatsu), and/or Red (chun)
• No suited tiles: Cannot contain any characters, bamboo, or dots (numbered tiles)

Since honor tiles cannot form sequences (only triplets or pairs), tsuuiisou hands always consist of:

• Four triplets of honors
• One pair of honors

Strategic Considerations

Toitoi Requirement: Because honors cannot form sequences, tsuuiisou automatically includes toitoi (all triplets). However, yakuman overrides the toitoi yaku, so you don’t score both—only yakuman.

Limited Tile Pool: Only 28 honor tiles exist in a mahjong set (four each of seven types). Building a hand entirely from this limited pool is challenging but more feasible than other rare yakuman.

Open-Friendly: Like most honor-based yakuman, tsuuiisou maintains full yakuman value when open. You can call pon on honor discards without penalty, significantly speeding up completion.

Telegraph Risk

Honor-heavy hands become obvious quickly. Once you’ve called pon on two or three different honor types, opponents recognize either tsuuiisou or daisangen potential and stop discarding honors. You’ll be forced to self-draw the remaining tiles, which can be difficult given the limited honor tile pool.

Yakuhai Foundation

Even incomplete tsuuiisou hands provide strong scoring through yakuhai (value triplets). Any triplet of dragons or winds matching your seat/round wind contributes 1 han. A hand with multiple yakuhai triplets scores well even if tsuuiisou doesn’t complete.

Compatibility

Tsuuiisou cannot coexist with:

• Chinitsu, honitsu: These require suited tiles, while tsuuiisou forbids them
• Tanyao: Requires simples (2-8), while tsuuiisou uses only honors
• Any sequence-based yaku: Honors cannot form sequences

Usage Example

You draw several honor tiles early and commit to tsuuiisou. You call pon on White dragons and East winds. Later, you self-draw triplets of South winds and Green dragons. Your final hand: White-White-White, East-East-East, South-South-South, Green-Green-Green (four honor triplets), plus a pair of Red dragons. No suited tiles at all. When you win, you declare tsuuiisou (yakuman), scoring 8,000 base points (32,000 total for non-dealer) or 12,000 base points (48,000 total for dealer).

Related Terms

Honor Tiles: Winds and dragons. Tsuuiisou requires only honor tiles.

Jihai: Japanese term for honor tiles. Tsuuiisou is composed entirely of jihai.

Toitoi: All triplets yaku. Tsuuiisou always includes toitoi since honors cannot form sequences.

Yakuman: The highest-value hand patterns. Tsuuiisou is one of the standard yakuman.