Reference:https://naotabi.com/jigokudaniyaenkoen/
https://thegate12.com/jp/article/106
https://itta.me/article/11057/
https://www.travel.co.jp/guide/article/18387/#:~:text=%E4%B8%96%E7%95%8C%E3%81%A7%E5%94%AF%E4%B8%80%E7%8C%BF%E3%81%8C,%E3%81%AB%E3%82%88%E3%81%8F%E5%8A%B9%E3%81%8D%E3%81%BE%E3%81%99%E3%82%88%EF%BC%81