Traffic access through Aso is improving, according to the Kumanichi, with a 6.6 kilometer stretch of Yamanami Highway blocked by landslides reopened and a road from Kikuchi to Aso now clear (both indicated by blue on the linked map - red is still no-go). http://kumanichi.com/news/local/main/20160525012.xhtml
If you have never driven Yamanami Highway in the sunshine - where the days are longer, the nights are stronger than, well - check it out here (substitute Ventura Highway and you’ll get the gist). It is a lovely drive that you will never forget. https://www.youtube.com/watch?v=cQCjHC0m54E