Hwatu is the most famous playing card set in Korea and Japan. We can often see that people play Hwatu with their family on Korean Holiday. But there is a prejudice that Hwatu is only for adults. And there was only one style of Hwatuunlike trump cards.
Hanafuda / 花札 : [wikipedia] There are twelve suits, representing months. Each is designated a flower, and each suit has four cards. Typically, each suit will have two normal cards and two special cards.
Hanafuda ("flower cards") are used to play a traditional Japanese card game called oicho-kabu (おいちょかぶ). The worst hand in oicho-kabu is an 9 and 3 (yattsu, ku, san), phonetically expressed as "ya-ku-za".