Since 2004, Mr. Watanabe has been working with the Kōka City Board of Education Historical Cultural Heritage Division to compile and translate the 70+ relevant documents, which they claim will clear up many of the mysteries surrounding the historical ninja.
A booklet summarizing the documents (complete with annotations and explanations) will be published by Kōka City in May of 2017.
However, a series of family documents discovered by Toshiyuki Watanabe of Kōka City, Shiga Prefecture, Japan may shed some light on the truth within the shadows.