The affairs of the nobility are fraught with strangeness and uncertainty. The nobility has a good amount of internal bickering, territorial disputes, and authoritarian political détentes. So, why, then, does Captain Hiro and the crew of the Krishna find themselves butting into the affairs of Count Abraham Dalenwald of a distant star system? Few good things come from dabbling in the affairs of nobles. But in Hiro's case, the poor guy doesn't really have a choice.
REBORN AS A SPACE MERC v4 closes the short saga of Hiro's saving and subsequent defense of an orphaned girl (Christina Dalenwald). The previous volume poked and prodded what might happen if happenstance happened too urgently; the current volume takes its time spelling out the details of the consequences thereof. The Krishna teams up with Lieutenant Commander Serena Holz' pirate-hunting crew to smack down a few pesky rebels, while elsewhere plays the role of bodyguard and teammate to Count Dalenwald to fend off a local rebellion. Nobles. Troublesome bunch, aren't they?
The current volume doesn't stock its pages with as much kinetic action as the novel series' previous volumes, but the author manages to incorporate just enough dogfighting and space slaughter to keep the pace. Similarly, the current volume keeps things superficial, in terms of character dynamics, by dwelling on the crew's latest addition (Mei, the maid android) only long enough for a brief recap of the protagonist's origin story and relational curiosities.
Readers interested in seeing Captain Hiro simultaneously impress and make a mess of his relationship with nobility will enjoy REBORN AS A SPACE MERC v4. However, readers vying for a slightly deeper, more invested (or extended) conflict will be left wanting. For example, while one doesn't doubt how fun it is to see Hiro don his heavy exoskeleton and mow down some enemies alongside a maid android specked for battle, the fight scenes are scant and the tussle with the baddie at the end is anticlimactic.
Of better news, the book's fine-tuning of the author's universe-building shines in spots. Space travel earns acute focus, as the Krishna ventures from the Cierra System, via interstellar gate, through multiple neighboring star systems, on toward Dalenwald's neighborhood, the Dexar System. The scope and scale are difficult to fathom, for both reader and protagonist, but the notion of an intergalactic empire capable of governing such a wide expanse is very intriguing.
Also of note, everyone's favorite drunken, lovelorn military lady spills the beans on a curious what-could-have-been moment for Hiro. Apparently, Hiro's shot at knighthood isn't out of the question (e.g., What would happen if he worked for Dalenwald full-time?). Neither is an opportunity to push his way into the upper echelon of the Grakken Empire. Apparently, there's this thing called the First-Magnitude Star's Cross of Brilliance, or Gold Star, for short. It's essentially the highest civilian-soldier distinction and earns one the salary and status of a low-level noble (Serena: "Given the right battlefield, I'm sure you could get one," p. 87).
REBORN AS A SPACE MERC v4 is a fun but less demanding volume of the novel series. The novel's most remarkable highlight is oddly buried early in the very first chapter, whereupon Hiro discusses Simulation Theory (or, the simulation hypothesis) with Mei, concerning his origin. The space merc counters the maid's commentary with a truly phenomenal, almost throwaway bit of existential dithering: "[I]t sounds more likely that instead of somehow entering a video game universe, I came out of a video game or some other universe that's simulated inside this one" (p. 20). Since the first volume, this novel series has broken the isekai mold in small but deliberate (purposeful) ways, and one would find it extraordinary for the author to continue peppering small snippets of commentary, such as this, in future stories.
As for the current volume, Chris was a bit of an annoyance, and so it's probably best if she's shuttled elsewhere. Too many clingy characters can feel draining. Although one questions the English-language publisher's unforced error of placing Dr. Shouko on the back cover when the character isn't even mentioned in the novel. Regardless, the current volume is a fine but less compelling addition to Hiro's wayward saga.