Thread:Takashichea/@comment-29818919-20161024152007

I found a source for extras by Ohtaka including things such as promotional art and bonus things such as the post card book. It also has a few pictures of concept art.

https://translate.google.co.uk/translate?hl=en&sl=pt&tl=en&u=https%3A%2F%2Fforumproject.zlx.com.br%2Ftopic%2F31915-galeria-ohtaka-backstage-capasextras%2F%3Fpage%3D2

Just in case you need it there's the link. 