A couple of big questions there!
I wonder what Shigeru's inspirations are for his works?
There’s a few names we’ve uncovered that are worth mentioning. Inagaki Taruho and Miyazawa Kenji are both authors that Tamura has mentioned and from whom it’s easy to see an influence (e.g. One Thousand and One Second Stories, and Night on the Galactic Railroad). For art, there’s the Belgian surrealist painter and sculptor, Jean-Michel Folon.
In the manga world, the biggest is Kamosawa Yuuji. Although he was essentially Tamura’s contemporary (he debuted in Garo a couple of years earlier than Tamura), it seems there was a definite influence. Like Tamura, he also took a lot from Inagaki Taruho. We’re hoping to translate some Kamosawa in the not-too-distant future.
I'm also curious to how this work (from 1996) might be related to Phantasmagoria Days (from 2000)
It’s an interesting question! I personally think of it like an alternative timeline, using ideas that also show up elsewhere. Off the top of my head, I don’t know when the first appearance of the Lancelot-style robot is, but it definitely shows up in his 1989 Phantasmagoria art book.
I don’t recall seeing it in any of his earlier manga from the 70s/80s.
In any case, there’s other ideas that reappear in different works. For example, the planet Dana that’s mentioned in Phantasmagoria Days is also mentioned in the Glassy Ocean OVA, and there’s a picture book for adults called ‘Dana’ which is set on the planet (and features a protagonist that looks a lot like Dr. Hoop).
I think that most of his work, especially from the mid-80s onwards, is basically an expansion of the set of ideas he developed in his early manga. Even when the details differ slightly, it still has the feeling of his singular world.