Ryanpeikou (Two Pairs of Identical Sequences)

Two identical sequences (e.g. two 234m) in the same suit, in a closed hand. 1 han, closed-only — any call kills it outright. Replaced by ryanpeikou (3 han) when the hand contains two such pairs of identical sequences.

A closed hand of exactly seven distinct pairs. The seven pairs must all be different tiles — duplicates of the same pair count as one. Scores a flat 25 fu and pairs well with honor-heavy or mixed-suit hands that resist forming triplets.

A closed hand of all sequences, with a non-yakuhai pair and a two-sided (ryanmen) wait. Adds zero fu beyond the base — pinfu tsumo stays at 20 fu, pinfu ron rounds to 30. The high-frequency partner of riichi and tanyao in closed-attack templates.

A hand containing no terminals (1s, 9s) and no honor tiles — only 2-8 of suits. 1 han, open or closed under modern kuitan rules; strict rulesets still require menzen. The workhorse open yaku, easy to lock in whenever the early hand is heavy on middle tiles.

A hand made entirely of one numbered suit. 6 han closed, 5 han open — the highest non-yakuman han floor in the catalogue. Common when one suit floods your hand; stacks naturally with pinfu, iipeiko or ittsu inside the same suit.