Toitoi

Toitoi

Toitoi (対々 / 対々和) is a 2-han yaku in mahjong where all four melds in a winning hand are triplets (either pon or kan). Also known as toitoihou, this yaku requires a hand composed exclusively of triplet combinations, creating a distinctive “all pairs” pattern in the melds.

Detailed Explanation

In standard mahjong hand composition, a winning hand consists of four melds plus a pair (the eye). Most hands use a combination of sequences (chow) and triplets (pung). Toitoi, however, restricts all melds to triplet-only combinations, eliminating sequences entirely.

Hand Structure

A toitoi hand follows this pattern:

• Four triplets: Each meld must be either a pon (明子, a claimed triplet) or a kan (槓, a quadruplet)
• One pair: The eye can be any pair

For example, a valid toitoi hand might include:

• Pon of 1-circles
• Kan of 5-bamboo
• Pon of east wind
• Pon of white dragon
• Pair of 3-characters

Scoring Value

Toitoi carries a base value of 2 han (two doubles). This means:

• Combined with other yaku, it contributes 2 han to the total hand value
• A hand with only toitoi and the base meld (no other yaku) scores as a 2-han hand
• When combined with additional yaku, the han values accumulate

Strategic Considerations

Toitoi hands are relatively difficult to achieve because they require drawing or claiming three of the same tile four times over—more restrictive than mixed hands using sequences. However, they offer strategic advantages:

• Flexibility in sequences: Since sequences aren’t required, players have more freedom in discarding and claiming tiles
• Combination potential: Toitoi frequently combines with other yaku such as honortai (honors triplets) or yakuhai (dragon/wind triplets)
• Kan opportunities: The ability to form kan (four-of-a-kind) within a toitoi hand can trigger additional scoring bonuses

Related Mechanics

Toitoi interacts with other hand-building concepts:

• Kan: When a kan is formed within a toitoi hand, the kan itself may provide additional scoring
• Yakuhai: Triplets of dragons or seat winds automatically qualify as yakuhai, often appearing in toitoi hands
• Chitoitsu: While chitoitsu (seven pairs) is a different yaku entirely, both emphasize pairs and triplets over sequences

Usage Example

Consider this scenario: A player has collected three circles (1, 1, 1), three bamboo (5, 5, 5), three east winds, three white dragons, and a pair of 3-characters. Upon drawing a winning tile that completes one of these combinations, the player declares a win with toitoi.

If this hand also includes yakuhai (such as the white dragon triplet), the scoring would be calculated as toitoi (2 han) + yakuhai (1 han) = 3 han total.

Related Terms

• Pon (碰): A claimed triplet of identical tiles, essential to forming toitoi
• Kan (槓): A set of four identical tiles; can substitute for a triplet within toitoi
• Meld: The four combinations that form a mahjong hand; in toitoi, all four are triplets
• Yaku: The winning hand patterns that qualify for scoring; toitoi is one such pattern
• Triplet: Three identical tiles; the foundational unit of toitoi
• Mangan: A hand worth 2,000 points; toitoi hands often score at this level or higher when combined with other yaku
• Yakuhai: Triplets of dragons or seat winds; frequently appears alongside toitoi
• Chitoitsu: An alternative yaku emphasizing pairs rather than triplets