Examining Japanese Survey Results on Religion
The following plot displays results from a survey about religion by NHK.
It should be noted that similar surveys could show very different results.
If this were multi-select, more people might select Shinto.
This survey specifically asked for religions that people “actually” believed in^1. If this instruction was not included, many of the people who replied “None” may answer Buddhism or Shinto.
Also, many people who answered “None” still visit Buddhist temples and Shino shrines on various occasions.
1: Stated as「あくまで，あなたご自身が，ふだん信仰している宗教」