Very similar to G UZAKI Tile Efficiency 2 but it's different!
Now WWYD and WHY?
Who is G Uzaku?
Mahjong books author. And he is also works for other Mahjong tactics books as Proofreading.
He prefer play real mahjong rather than internet Mahjong games.
『麻雀 傑作「何切る」300 選』
300 Selected WWYD (Blue)
Mahjong established tactic 301 selected WWYD (RED)
Uzaku Style MJ Studies "Tile Efficiency"
Picked Tile efficiency related subjects from Blue and Red version and adding more.
Highly recommended for players who just started and not winning hands often.
G Uzaku also running his blog
(Slashing MJ Books! Slashing MJ games!)