In the world of baby-naming, Tomo is a unisex name of Japanese origin that references intelligence. Tsukihiro may be based off of "tsuki," or moon, with the male name ending "-hiro." Alone, the Japanese unisex name "Hiro" generally means generosity or prosperity.

The other names don't seem to have particular meanings, but are still "real" names (save for Tsubarel, as far as I'm aware). In Ponako (which is coincidentally Polish, I believe...?) "-ko" is a common Japanese female name ending. I believe Kato-shi, with the hyphen, happens to be a city. Satoshi, on the other hand, is also a reference to intelligence or wit, but one letter difference can change things entirely. Tsubarel sounds fun and may be completely original or derived from one or more sources.
This doesn't mean the names were created/suggested for any reason aside from sounding good, but just some extra meaning to go along for people interested in that kind of stuff!~ I am too fascinated in name meanings myself and somehow end up browsing baby-naming sites a lot even though I have absolutely zero plans for one anytime soon, but sometimes they're awesome for finding meaningful character names.
I picked a name I narrowly preferred over the others, but the deciding factor between choosing either it or my second choice was that the second choice is also that of a character I can't stand at all. :X