Shozan means the rank of temple 'Zenrin', temples of the Zen sect in Japan, which is under the ranks of 'Gozan' and 'Jussatsu.'
In China, 'Kassatsu" corresponds to Shozan.
In 1321, the then head of the head family of the Hojo clan Takatoki HOJO who was a former regent of the Kamakura bakufu (Japanese feudal government headed by a shogun) constructed Sujuji Temple in Bengayatsu in Kamakura, which is now ruined, and given a title 'Shozan' as the rank next to 'Gozan' to the temple, which was the oldest example of 'Shozan.'
Thereafter, the title 'Shozan' was given to Zenrin that had not been given the title 'Gozan' or 'Jussatsu.'
In principle, 'Shozan' should have been designated by the decree of Seii Taishogun (great general who subdues the barbarians) of the Muromachi shogunate government as in the case of 'Gozan', but as the upper limit was not set for the designation, commands from Emperor Daijo of the Northern Court or even qualifications by the Southern Court, which was the enemy of the bakufu, were confirmed so that 'Shozan' was given to a lot of 'Zenrin.'
Later, 'Shozan' were placed in all the provinces except for the seven provinces of Yamato, Izumi, Shima, Hida, Sado, Oki, and Buzen, and they numbered no less than 230.