Ikkitsuukan: Difference between revisions

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* [http://tenhou.net/0/?log=2014030918gm-0089-0000-22ae5fde&tw=2&ts=6 Ittsuu] as [[kazoe]]
* [http://tenhou.net/0/?log=2014030918gm-0089-0000-22ae5fde&tw=2&ts=6 Ittsuu] as [[kazoe]]
}}
}}
'''Ikkitsuukan''' {{kana|一気通貫}}, or '''ittsuu''' {{kana|一通}} for short, is a [[List of yaku|yaku]], defined as three distinct [[mentsu|tile groups]] containing 123, 456, 789 of one suit. Collectively, the three groups form a complete single suit straight of 1 through 9. Naturally, in English terms, this hand can also be noted as a "straight", similar to the poker hand of the same name. This hand may be played open or closed.  When open, the hand [[Kuisagari|loses value]] of one han.
'''Ikkitsuukan''' {{kana|一気通貫}}, or '''ittsuu''' {{kana|一通}} for short, is a standard [[List of yaku|yaku]], defined as three distinct [[mentsu|tile groups]] containing 123, 456, 789 of one suit. This forms a single suit "straight" of 12345689, similar to the poker hand. This yaku can be scored open or closed, but if in an open hand, it [[kuisagari|loses 1 han]] of value.


==Tile diagram==
==Tile diagram==
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===Counter example===
===Counter example===
Having all the tiles from 1-9 in one suit is not sufficient to compose this yaku - they must form as sequences of 123, 456, 789.
Having all the tiles from 1-9 in one suit is not sufficient to compose this yaku - as mentioned above, they must form as sequences of 123, 456, 789.


{{#mjt:12344m56p}} {{#mjt:5'677'89m}} Waiting for: {{#mjt:4p}} or {{#mjt:7p}}
{{#mjt:12344m56p}} {{#mjt:5'677'89m}} Waiting for: {{#mjt:4p}} or {{#mjt:7p}}

Revision as of 22:54, 14 June 2024

Ikkitsuukan
Type Yaku
Kanji 一通 or 一気通貫
English Straight
Value 2 han
1 han (open)
Speed Fast
Difficulty Easy

Ikkitsuukan 「一気通貫」, or ittsuu 「一通」 for short, is a standard yaku, defined as three distinct tile groups containing 123, 456, 789 of one suit. This forms a single suit "straight" of 12345689, similar to the poker hand. This yaku can be scored open or closed, but if in an open hand, it loses 1 han of value.

Tile diagram

Winning tile: or

Open

Winning tile:

Formation

While the hand shows a complete 1-9 grouping from a particular suit, it is best to view the long cluster as three separate groups of: 123, 456, and 789.

Counter example

Having all the tiles from 1-9 in one suit is not sufficient to compose this yaku - as mentioned above, they must form as sequences of 123, 456, 789.

Waiting for: or

In this counter example, the tiles 1-9 for one suit are in the hand, but ittsuu would not be counted. Instead, they are grouped as 123, 567, and 789, with 4-man functioning as the pair.

Discard characteristics

Hands aiming for ittsu often lack a particular suit, as a good number of one suit is collected in the hand.

Compatibility

^ Ippatsu requires riichi to be of any use.

RCH DRI IPP SMO TAN PFU IPK ITT YAK SDJ SDO TOI SNA SNK CHA JUN RPK SSG HRO HON CHN CHI RIN HAI HOU CHK
ITT

Ittsu requires three groups to be sequences, leaving room for only one other tile group. Yaku that require more than one triplet - sanshoku doukou, sanankou, sankantsu, shousangen, toitoi - are thus incompatible. Similarly, sanshoku and ryanpeikou are incompatible because there is no room for their patterns. Chiitoitsu, which does not use mentsu, is likewise incompatible. The 456 sequence invalidates chanta, junchan, and honroutou, while the 123 and 789 sequences invalidate tanyao.

Ittsu can often be combined with honitsu/chinitsu, as the ittsu is already composed of 9 tiles of the same suit. Pinfu also combines well; however, if the ittsu section is not complete, the hand would be subject to to takame and yasume (only one of two waiting tiles would score this yaku).

Vs sanshoku

Ittsuu requires three out of the four tile groups to be composed of sequences: 123, 456, and 789. Sanshoku also requires at least three groups of sequences. Sometimes, a hand may be 1-shanten for both yaku because of composition, forcing players to decide one or the other.

Usage

Despite being easy to memorize, ittsu is one of the more difficult yaku to obtain.

Sanshoku is worth the same (2 han) and has a similar requirement (3 identical sequences). However, sanshoku occurs more than twice as often as ittsu. This is likely because ittsu's 123 and 789 sequences are harder to form than other sequences.

External links

Ikkitsuukan in Japanese Wikipedia