All it takes is a whiff and a sip of shōchū to realize it is markedly different from the more common nihonshu (which Westerners call "sake," although in Japanese, sake is a catchall word for all alcoholic drinks).
It is, too, a much more recent arrival. Way back in 689, the Imperial Court in Nara had already established a sake-brewing department, which suggests its origins predate even then.
On the other hand, the first evidence of shōchū in Japan -- after it probably came with traders from China or Korea -- is graffiti dated 1559 that was written by a carpenter in a shrine in the city of Okuchi, present-day Kagoshima Prefecture.