When one thinks of mummies, they likely imagine something scary/creepy and in the context of fiction, dangerous and bad. For me, the first thing that comes to mind is what you'd see in something like The Mummy. This anime brings to light something that I doubt anyone has ever even considered: keeping a mummy as a pet. Or better yet, a mummy being adorable (overwhelmingly so).
Story/World-Building
As I mentioned before, there isn't much of a story. The mummy, Mii-kun, gets introduced within the first few minutes. Then it's basically just SoL centered around him and Sora (and the rest of the cast as they get introduced across the anime). Okay, there's a bit more to it than that.
One big theme throughout this show is how each of the characters have some sort of personal/internal problem. And for whatever reason, they cross paths with a specific youkai (or in Sora's case, a mummy) that by sheer coincidence so happen to be the catalyst for the solution. I will admit, on paper and thinking back on it, this sounds pretty cheesy/cheap. Maybe it is. But the way it was executed was just perfect, at least for me. There was a good flow and pacing to all this and it also didn't eat up the entire 12 episodes (about half or so).
Characters
While I didn't find the characters all that interesting, they were still fine. A majority of the development went to Sora and his friend Tazuki. I liked their relationship and how it grew throughout the season. It's worth mentioning that there is absolutely no romance (or even fan-service) in this. So if you're one who wants any of that stuff then you'll be disappointed.
The rest of the cast was alright, but just didn't receive close to as much attention. Regardless, I liked everyone. Especially Kaede. Apparently, she's actually Sora's aunt and not his sister. That blew my mind once I realized that.
Art/Animation
I thought the art looked pretty good. Everyone had a distinct design and I just liked all the colors used. The art style felt strangely familiar to something else I've seen before, but I couldn't put my finger on what exactly. If someone knows of something similar, please let me know. But yeah, I didn't find any issues with how anything looked. I think my opinion would be the same with the animation. Everything looked good to me. 8-bit gets a thumbs up from me.
In this anime, there are a lot of interactions and scenes involving the various youkai (and mummy). They don't actually ever talk, but despite this, they are able to perfectly encapsulate emotion through the use of various animations (a common one being flower-like shapes that spin around their heads). I think that this in tandem with the sound used for their voices was just excellent. I also don't think I've ever seen this done before in an anime either, so it was interesting to see.
Audio/OST
I loved the OP and ED for this. Most of the time, I wouldn't skip either. Aside from just being good songs, I just think that they fit the vibe of the show really well. Additionally, the OST was also perfect. I was surprised to see that Kenichirou Suehiro (I loved his work in Re:Zero and Goblin Slayer) was the man behind all the wonderful music. No complaints here. The rest of the audio was splendid too. There are a few scenes with rain and the ambience from that was just perfect. So this all gets full marks from me.
Conclusion
I think it's pretty clear what my thoughts on this show are. Just go check it out. It's nice and comfy. While it is a shame that it never got a second season, it does end at a good place. And the manga is apparently still ongoing and I'm sure by now it's well beyond what got adapted here. So if you liked this, I'd check that out too. I haven't yet, but I probably will at some point.
I came really close to giving this a 10/10. However, I try to reserve a perfect score for my absolute favorites. While this anime did check a lot of the right boxes for me, I just don't see it making that list. That being said, it's near perfect (in my opinion).
I give How to Keep a Mummy a 9/10.