So... is the proper tag "tsukuyomi" or "tsukuyomi moonphase"? Thanks.

There are a few other images tagged with either, but the series is specifically "Tsukuyomi_Moonphase".
It should be fine as is with both. I'm going to add nekomimi.

I just put in an alias request tsukuyomi --> tsukuyomi_moonphase. (And added the characters in.) Yes, former has far more, but that's the beauty of an alias, people can keep using it if they want.

I'll also mass edit it, though I'm not sure if I need to, the alias might take care of that by itself... I think I'll do it but then go ask in the forums about that for next time.