Willow [柳 - やなぎ, yanagi] is the name of a suit in traditional hanafuda decks. In the standard Japanese ordering, it is generally taken to be the eleventh suit, representing the month of November [十一月 - じゅういちがつ, jūichigatsu] or the numeral 11. Originally, the cards in this suit all featured willow trees with hanging branches. There is one Chaff card, one Plain Ribbon, one Animal, and one Bright.
The Willow Chaff is known as the Lightning card [鬼札 - おにふだ, onifuda, lit. “demon card”], and in the modern hachihachibana pattern the hanging willow branches on it have been altered to a more abstract grey and red cyclone shape, with various details (such as drums, windmills, a demon’s claw, etc.) underlying the coloration, depending on the specific deck.
The other three cards of the suit have maintained the willow tree motif. The Animal card features a long-tailed, red and yellow Swallow [燕 - つばめ, tsubame] flying between the drooping branches. The Bright card is generally known in English as the “Rain Man,” and features a human figure holding an umbrella under a willow tree beside a stream. In modern Japanese versions of the Rain Man card, the person depicted is prominent Heian era calligrapher Ono no Michikaze [小野道風 - おののみちかぜ], also known as Ono no Tōfū [おののとうふう], observing an orange frog in the lower left corner of the card.
In a few games, including Tensho, an alternate month ordering is used, with the Willow suit representing February or the number 2 instead. On the other hand, in the Korean suit order, Willow is considered to represent December or the number 12.