Ryakudan

Really common for some legions. It was the Revenant Legion (blood angels) whole thing.

Read the raws till chapter 166, and while enjoyable, it has some big flaws (there's also some slight world hoping), which is weird, when there's load of potential treads in their main world, also MC stops feeling like hachiman after a while, specially when interacting with Non oregairu characters. MC also isn't proactive. Your sister school suffers a masacre, and he pretty much doesn't acknowledge it(neither does Komachi)

if you're going to translate you should translate the whole novel and not leave a hole hoping the readers find another translation

isn't she Vali?

It's not a bad story, but sadly not for me, the plot twist at the end of the first vol was good, but I don't like those type of characters. then again that's taste not quality.