Hey! It's not a fantasy isekai. I'm honestly amazed; I didn't think that was possible.
To sum up my thoughts, Reborn as a Space Mercenary is a pretty average isekai, but with the uniqueness of not being a: fantasy, b: revenge, c: 'reincarnated as', or D: all of the above. Nothing horribly offputting, unlike a lot of things I've read recently, so it deserves some praise for being actually kind've enjoyable to read.
Story? What story? Our MC wakes up in his magically-there ship, saves some girls from rape/poverty, and forms a harem all while his only goals are 'get lots of money from mercenary work', 'stay out of the government issues', and 'buy a house on a planet.' It's not a terrible story, but it doesn't have any driving forces, and the world isn't interesting enough to carry the story off of that.
Art is pretty good, actually. Nothing looks horrible to me, though the art is pretty basic. Design-wise, everything is very generically sci-fi, and the station designs are stolen straight from Elite Dangerous. Actually, basically everything is taken from Elite or Star Citizen. Not that that's a bad thing, given that those are the best two space sims out there...
Character is easily the worst part of the manga. Our MC has functionally none, other than liking cola and being completely unbothered by participating in the, and on his own, murdering of dozens or hundreds of fellow humans. His first harem member, cute-girl, has the character traits of, uh, liking food, not knowing how to do anything, and that's it. The other harem member, elf-girl, is a crappy tsundere. The background characters are nothing to write home about, and the rich-girl is your classic 'gets drunk' stoic type.
Still, I enjoyed reading it to enough of an extent that I binged all 18 chapters without asking 'why am I doing this?', so that's marks in its favor. Give it a try. Not going to be the next Slimesekai, but it's fine enough for the genre.
Story: 4
Art: 6
Character: 3
Enjoyment: 6
(19/40)
Overall: 5/10
