I remember looking up the significance of cicadas some time ago and I remember that in Rika's Dear You image song (Dear You -Hope-), she describes her life being ephemeral like the cicada.
"The popular belief that evening cicadas die after the sun sets reminds us that summer will come to an end sooner than later, and we should enjoy while we can. Ultimately this can also be extended to life itself." Something I read from
this site.
EDIT:
Now I have a question. I don't know much about Shintoism but I've been trying to research on it. Is Oyashiro-sama/Hanyuu considered to be a "Shinto god"? Or would the Oyashiro-sama belief be considered its own religion, separate from Shintoism?