Without any news from Minami there is little keeping the thread alive.
留菜 would be a perfect ateji for Luna/Runa,
留 can be pronounced Ryuu, To, Tome, Todo or Ru in normal writing
菜 can be pronounced Sai and Na.
Anyway in http://c10029847.circle.ms/oc/CircleProfile.aspx they show the furigana...