Infact it's not rare that among the Japanese believers, there is people that follow both religions. Another example of the extreme paradox of Japanese culture.
Nowadays the most of Japanese people are not very religious and they go to the temple for praying very few times during the year.. perhaps just once at the last day of the year. The most common religions are the Shinto and the Buddhism that are actually quite similar.
Infact it's not rare that among the Japanese believers, there is people that follow both religions. Another example of the extreme paradox of Japanese culture.