noun
hand of only 1-point cards (hanafuda)
In hanafuda, a dealt hand consisting entirely of 1-point cards (kasu). This is a scoring combination (手役) that awards points.
See also: 手役
空素ができたら、すぐに勝負を宣言できる。
If you get a hand of only 1-point cards, you can immediately declare victory.
手役 is the general term for scoring combinations in hanafuda, while 空素 is a specific hand consisting only of 1-point cards.
The term is composed of 空 (empty, nothing) and 素 (plain, simple), referring to a hand with only low-value cards. The exact historical derivation is uncertain.