This one is full of Japanese culture—from guardians, youkai, and that ceremony at the end of it—I'm really curious about what's more to those.

It's better since I'm more familiar with the place (islands in the Seto Inland Sea)

Oh so those islands are real? I thought Shiojima was a fictional one because I haven't heard of it. Now this kinda made me curious about Japan's geography. And yes, you can really appreciate more the details in its story if you're familiar with its culture, so maybe I'll try studying its mythology and culture so that I can appreciate it further the second time I watch it.