If this was intended to be a short manga, I think it did fairly well.
But if it was axed—that’s unfortunate. It feels like the author had plans to show more, but the pacing was too fast and made everything feel rushed. There wasn’t enough time to connect with the characters, and we didn’t get to see their journey to revive Kyuu or what happened after they got back together.
Still, it’s a happy ending, so I’d probably give it a 7 or 8. I enjoyed reading it—the character designs were great, there was no harem, and it focused on a journey fueled by effort and a promise to fulfill. Cool fight scenes too.
That said, the translations leave a lot to be desired. I hope they improve in the future.