As a predominant religion in Japan I can point out the Buddhism. Buddhism seems to be a religion of a polytheistic tendency with many Hotokes under a Buddha or Sakyamuni. There are also many Shintoistic Shrines in Japan. Shintoism is a polytheistic religion. Most Japanese go for the New Year's prayer to Buddhistic temples or/and Shintoistic Shrines. I used to go for it to a nearby Shrine. I think Christianity is a minority group of religions.