Describe yayoi in Japanese culture

The Yayoi Culture is defined as Japan's first rice-farming and metal-using culture, and it is identified archaeologically with certain types of artifacts, especially pottery styles. But traces of metal artifacts and rice usually are not found in Yayoi sites, especially in the early ones, so pottery styles are generaly the main bases for identifying Yayoi sites. Also, the definition has been confused by a number of finds of rice, and even of rice paddies, in Jomon sites dating around 1000 B. C. (uncalibrated radiocarbon years ago), several centuries earlier than the pottery styles and other artifacts used to identify Yayoi sites. And recent finds of keyhole-shaped mound tombs (the defining trait of the Kofun Culture) older than A. D. 300 have confused the other end of the Yayoi period, overlapping by half a century or more with pottery styles that have been identified as Yayoi. Some archaeologist argue that we should keep the original definition of Yayoi and include as Yayoi much of what has to now been identified as Latest (or even terminal Late) Jomon. But other archaeologists are defining Yayoi by the pottery styles that traditionally have been used to identify Yayoi sites, and they have added rice farming to the description of the Latest Jomon culture, particularly in Kyushu. At the late end, most archaeologists seem to be dropping from "Yayoi" what used to be terminal Yayoi and are putting those late 3rd-century materials into the beginning of the Kofun Culture