https://www.pixiv.net/users/3473597
https://www.pixiv.net/stacc/yanagihirohiko
https://twitter.com/YanagiHirohiko
https://twitter.com/intent/user?user_id=814453743659847680
https://sketch.pixiv.net/@yanagihirohiko
http://yanagi-hirohiko.sakura.ne.jp
http://doujinshi.mugimugi.org/browse/author/1660/Yanagi-Hirohiko/柳ひろひこ/