♠ Yusui rule rule was made by Mr.Yamaguchi Yusui in 2006/03/13. This is new rule in future beyond Yamaguchi rule.
♠ However, this is not need now.
1P = 1st player (opener)|
2P = 2nd player (returner)
|At here, black and white turns are decided.|
♠ This rule has some variations.
* However, in variant 2, we can not use i13 opening.
♠ We can use great past study in all real games in this rule. When "I" am 1st player, "I" put i12 opening and suggest 2 for 5th.
♠ If opponent choose case (A), number will be decreased (two⇒one), and opponent get disadvantage in the game. Because Black has some advantage on condition "d12 + one 5th".
♠ If opponent want to beat me, she/he will choose case (B) here. Therefore, "I" put 4th freely. Opponent must choose Black or White on "my" condition 1st-4th moves.
♠ We can find new situation in Yusui rule more than Yamaguchi rule.
♠ 1st player put this opening and suggested three.
♠ In Yamaguchi rule, white has advantage in this condition. Because If white put freely in 4th move, white can use only strongest move without more swap.
♠ In Yusui rule, if opponent want to get White turn at here, she/he must change "suggested number" to "lesser than three". "lesser than three" is 1 or 2. When the condition, Black has some advantage about all 4th move in d12 opening.
♠ Therefore, opponent let "me" put 4th.
♠ At here, "I" put such this 4th.
♠ This is new situation more than Yamaguchi rule.