In Japanese, nouns do not have different singular and plural forms, so "haiku" is used as both a singular and plural noun in English as well.
ɪ n WORD_BOUNDARY d̠ʒ æ p ə n iː z WORD_BOUNDARY n aʊ n z WORD_BOUNDARY d uː n ɑ t WORD_BOUNDARY h æ v WORD_BOUNDARY d ɪ f ɹ ə n t WORD_BOUNDARY s ɪ ŋ ɡ j ʊ l ə ɹ WORD_BOUNDARY æ n d WORD_BOUNDARY p l ʊ ɹ ɹ ə l WORD_BOUNDARY f ɔ ɹ m z WORD_BOUNDARY s oʊ WORD_BOUNDARY h aɪ k uː WORD_BOUNDARY ɪ z WORD_BOUNDARY j uː z d WORD_BOUNDARY æ z WORD_BOUNDARY b oʊ θ WORD_BOUNDARY ʌ WORD_BOUNDARY s ɪ ŋ ɡ j ʊ l ə ɹ WORD_BOUNDARY æ n d WORD_BOUNDARY p l ʊ ɹ ɹ ə l WORD_BOUNDARY n aʊ n WORD_BOUNDARY ɪ n WORD_BOUNDARY ɪ ŋ ɡ l ɪ ʃ WORD_BOUNDARY æ z WORD_BOUNDARY w ɛ l WORD_BOUNDARY