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This is another yaku that doesn't get a lot of attention, also because it is not very easy to get. This was only my 3rd one in over 3000 hanchan so I decided to preserve it. It is always worth 4 han since you get the 2 extra han for the dragon pungs.
Correct me if I'm wrong, but I believe it is always a mangan, but without the kiriage rule (30 fu 4 han), I suppose it might not be.
(This occurs if both dragon pungs are exposed and you win by ron on a ryanmen wait with the other set also being a chow. I suppose you could also ron with a shanpon wait on a dragon pair, but this is getting confusing, so either way, there should be no tsumo, penchan, kanchan, or tanki waits, and no other pungs except for the dragons. I sure hope I'm stating this correctly.)

Anyway, I didn't find the one I got to be particularly attractive (it was nice, though) so I started to think of what would make it nicer. Honitsu! The last two chow sets in the same suit. Even better. Make them both pungs and get Toi-Toi. Wait. Make the pungs terminals. Honrōtō! Up to 10 han now, I think.
Hold on. Change the terminals to winds. Tsūiisō. Yakuman. Finally!

(I realize that with a concealed hand, I would have came up with a yakuman earlier, probably Suu Ankou, but then I wouldn't have had this much fun, and mahjong is supposed to be fun, eh, Saki. Besides, although probably basic to most of you, this was good practice for me.)

Heh, the other day I had a hand midway along that path. A Shousangen Honroutou Dora 3 for a Sanbaiman. An insteresting deviation along that path is that you can get to Kazoe Yakuman without resorting to the Tsuu Iisou. (Say, Shousangen Honroutou Honitsu Dabuton Haitei, if you don't want to stick to Dora 0).

Shousangen + honroutou is the most flexible way to make a kazoe yakuman without incidental yaku or dora. You can get shousangen + 2 dragons + honitsu + honroutou + toitoi + sananakou + sankantsu + double wind. Each one of those is worth 2 han, for a total of 16 han. You can remove for example sankantsu and half of the wind and still have a yakuman.

From above,

Anyway, I didn't find the one I got to be particularly attractive (it was nice, though) so I started to think of what would make it nicer. Honitsu! The last two chow sets in the same suit.

Just about 8 months and 1000 hanchan later, I got to see that nicer one. Being East with 2 dora was an extra bonus.
Such a hard yaku, even the symbol looks tough 小三元