rishiri.infoです。お騒がせしてすいません。
F.Y 様のヒント（ほぼ答えですね）
> set @male = 0, @female = 0;
> select if(性別 = '♂', @male := (@male + 1), @female:=(@female + 1)) as
> 性別順位
> from データ;

のお陰で

SELECT kiroku.scode As scode, sensyu.namae As namae, sei.seibetsu As
seibetsu,
min(if(kiroku.kcode = 4, kiroku.ktime, null)) As 4P,
min(if(kiroku.kcode = 9, kiroku.ktime, null)) As 9P,
min(if(kiroku.kcode = 13, kiroku.ktime, null)) As GP,
timediff(max(if(kiroku.kcode = 13, kiroku.ktime, null)),'06:00:00') As
tdiff,
@r1:=(@r1 + 1) As rank,
if(seibetsu = '男', @male := (@male + 1), @female:=(@female + 1)) As rank2
FROM kiroku,sensyu,kukan,sei
WHERE kiroku.scode = sensyu.scode
AND kukan.kcode = kiroku.kcode
AND sei.seicode = sensyu.seicode
GROUP BY scode, namae, seibetsu
ORDER BY tdiff DESC, rank2 DESC

男女別フィールド rank2 を追加して
男女別でも順位をつけることは可能になりました。
ありがとうございました！

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