Chiitoitsu 七対子

What It Is

Chiitoitsu (七対子, “seven pairs”) is fourteen tiles in seven pairs, every pair a different tile. Four of a kind is not two pairs here: hold all four 4s and the hand is incomplete.

Any tiles will do: numbers, honours, terminals. The wait is always a single tile, the partner of your last lone tile.

What It’s Worth

Chiitoitsu is 2 han, closed only. Its fu are fixed, and lower than most hands, so its value leans on the han you add on top: riichi, tsumo, tanyao and dora.

The good news is how readily it stacks. Riichi and chiitoitsu with a paired dora is already a respectable hand, and seven pairs of simples brings tanyao along for nothing.

Closed Or Open

Closed only, and there’s no way to call into it anyway: you can’t chi or pon a pair. The only call you might make is ron on your final tile.

How To Build It

Think about it when the deal gives you four or five pairs and few runs. Keep pairs, throw singles, and don’t let a pair grow into a triplet you can’t use.

With five pairs you’re two tiles away, and it often makes sense to keep both roads open for a while: the same pairs could become triplets for toitoi or a standard hand. Commit once the shape tells you which is closer.

The magic of chiitoitsu is that you choose your wait. Hold on to a tile that’s hard for others to keep, like an honour with one copy already discarded or a terminal nobody wants. Others throw it more freely, and it’s a fine riichi wait even though only a few copies remain.

Common Mistakes

• Counting a kan or four of a kind as two pairs. It isn’t.
• Ponning one of your pairs. That opens the hand and ends chiitoitsu on the spot.
• Sitting on a dead wait. If both remaining copies are visible, change tiles before you riichi.

What It Combines With

Riichi, menzen tsumo, tanyao, honitsu and chinitsu and honroutou (2 han) all count with seven pairs. Every dora you pair up counts twice. It can’t combine with pinfu, iipeikou or toitoi, which need sets, and seven honour pairs is the yakuman tsuuiisou.