I think I would have found this a stronger story if I knew less about Unit 731. That's not to critique Liu's accuracy--he's done a thorough job of research. It's just, I've read the sources he's working from. I've had the gut-punch moment when I comprehended the atrocities. And revisiting them here, through the thin lens of fictionalization Liu provides, can never hope to match the emotional impact of that first encounter.
For me, I think it would have worked better if the details had been elided, if the focus had been more firmly on Wei and Kirino and the notion that in studying history we destroy it. It's like a horror movie: hints and glimpses build more fear than straight-on shots of monsters, because your brain fills in the gaps. But that's speaking as someone who can
fill in those gaps, and I gather that for most of Liu's audience, Unit 731's name elicits more "huh?" than horror.