Bride of Demise is a novel by the author of Fremd Torturchen: Torture Princess, and similar to that, this one starts pretty gruesome as a young boy bleeding profusely and about to die is saved by a princess. Specifically a girl referred to as just "White Princess", who spreads her mechanical wings out from her body to show she's not quite human. Thus starts this military scifi action fantasy series about an orphaned boy in a military school enlisted to a secret elite squadron who fight using the powers of beings like the aforementioned White Princess.
Characters:
I think the characters were a bit weak. I think the author kinda had a hard time putting this interesting narrative in between the school life setting in a single volume. The school life 'scenes' were few, but kinda uninteresting. You get a few moments of two characters having a running gag, and one of those two characters is unusually quirky (sometimes harsh, sometimes lovey dovey). But most of the rest of the cast is kinda standoffish or quiet. Even the main character, Kou, is just very stoic, and forthright, and that's part of the plot, but still.
Each of the major characters are paired with a sort of bio mechanical being known as a Kihei. Some of these are like Iron Golems, some are animalistic or even humanoid, and then there's the special ones that are basically the Princess types. This includes the main characters Kihei, White Princess. She's kinda in a similar role to other protector servant knights in other series who want to devote themselves to a random boring guy for seemingly no reason (I'm sure you've seen this archetype before if you watch any anime). Now there is a bit more to why she devotes herself to Kou, but again, gonna have to read to find that out.
Intrigue / Plot Hook:
I think the overall setting is gonna be why you stick around, and the mystery of what the Kihei are, why Kou has this vague precognition and sense of destiny / duty towards pairing up with White Princess. The only issue is, that intrigue is mostly solved in this volume (and it's heavily implied what the Kihei are).
I did find myself struggling a bit towards the middle of the book. They did two encounters in a row that end with the characters having their backs against the wall with a seemingly insurmountable enemy group. I felt like maybe we should have seen at least one "normal" expedition for the group of Kihei owners, though again, there are story excuses for what happens.
The little nugget at the end that's supposed to entice you to read the next book isn't nearly enough of a hook to stick around as a reader I think, however I will read the next volume.