God in Shinto is able to be splited from the original Jinja and duplicate at another Jinja. This idea lead to increace the number of shrines when people would like to have Jinja in their neighborhood.
Usually the name of those duplicated Jinja is a combination of the name of God they brought to and of an area or a person.
That is why `Hachiman'or `Inari-jinja' are ubiquitous everywhere in Japan.
Especially, the shrines which enshrine `Hachiman' are the most. It is said the number of them is about 8000.
One of the reasons for the popularity is that Hachiman is assumed to be the 15th emperor, Oujin emperor, so each emperor in history believed Hachiman God.
Following that, many influential people in history such as Minamoto Family in Kamakura period, Ashikaga Family in Muromachi period and Tokugawa Family in Edo period believed in Hachiman God.
Also many samurai who support those family believed Hachiman God as God of battles and God who protects samurai families.
That lead to create many of Hachiman Jinja everywhere in Japan.
The second top (approx.4400 shrines) is ones whose belief is in Ise Jingu shrine.
The third is Tenmangu (about 4000 shrines), which enshrines Tenjin (Mr. Michizane Sugawara). He is God of study.
`Jinjatte donna tokoro? ` by Kikuko Hirafuji (publisher : Chikuma shobo)