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Boys' Day; the Tango Festival (May 5)
A traditional seasonal festival held on May 5, originally celebrating boys' growth and health. Now a national holiday under the name こどもの日 (Children's Day).
五月五日は端午の節句だ。
May 5 is the Tango Festival.
Almost always appears as 端午の節句 (the Tango seasonal festival). The word 端午 alone is rare in modern speech. Note the homophone 単語 (vocabulary word) — completely different meaning, different kanji.
Common collocations
Cultural note
Traditional customs include flying 鯉のぼり (carp streamers), displaying 兜 (samurai helmets) or 五月人形 (warrior dolls), eating 柏餅 (oak-leaf mochi) and ちまき (sweet rice dumplings), and bathing in 菖蒲湯 (iris baths). Since 1948, May 5 has officially been こどもの日 (Children's Day) as a national holiday.