Haikai (Japanese 俳諧 comic, unorthodox) is a poetic genre that includes a number of forms which embrace the aesthetics of haikai no renga, and what Bashō referred to as the "poetic spirit" (fūga), including haiku, renku (haikai no renga), haibun, haiga and senryū (though not orthodox renga, tanka or waka).

"Haikai" is sometimes used as an abbreviation for "haikai no renga".

Matsuo Bashō (1644-1694) is one of the most famous poets of the Edo period. For Bashō, haikai involved a combination of comic playfulness and spiritual depth, ascetic practice and involvement in human society. The first time in Japanese literary history that the word haikai was first used was at the beginning of the 10th century. Haikai is an idea that goes beyond material forms of art, its a mode of thinking, speaking and acting. Matsuo Bashō was the greatest figure active in Japanese haikai during the latter half of the seventeeth century. He did not only compose haikai poetry but he also created masterpieces in a variety of genres, including renku(linked verse), haibun(haikai-style prose), and haiga(haikai paintings). Bashō’s haikai treated of the ordinary, everyday lives of commoners. In contrast to traditional Japanese poetry, he portrayed figures from popular culture such as the beggar, the traveller and the farmer. In crystallising the newly popular haikai he played a significant role in giving birth to modern haiku, which reflected the common culture