Japanese castles I've visited: #6 Azuchi Castle Ruins in Shiga Prefecture. Only ruins are left, but some of the most extensive ruins I've seen. If you're in Shiga or a fan of Oda Nobunaga, then it's worth a visit!
Japanese castles I've visited: #62 Morioka Castle in Iwate Prefecture. Only ruins are left, but the park is really beautiful! More about it here in my blog: http://zoomingjapan.com/travel/morioka-castle-site-park/
Japanese castles I've visited: #61 Mihara Castle Ruins in Hiroshima Prefecture. Ok, this wasn't a very interesting castle. Very few ruins are left, but they are right behind JR Mihara Station. I went there when it was already dark.