Ame-shikō; Rain Four Brights
A hanafuda yaku consisting of the Rain Man (Ono no Michikaze) card and three other 20-point bright cards. Worth 8 points in standard rules. Often considered a variant of Shikō (Four Brights) that includes the Rain Man instead of a fourth regular bright.
See also: 出来役
Ame-shikō is a yaku formed by the Rain Man card (Willow with Ono no Michikaze) and three other bright cards.
If you're aiming for Ame-shikō in hanafuda, secure the 20-point Willow card early.
Compound of 雨 (ame, 'rain') + 四光 (shikō, 'four brights'), referring to the inclusion of the Rain Man card in this four-bright combination.