It's a good thing that this is the final book in the “other other world” arc, because while there is technically enough plot to round the volume out, it is feeling a little thin. The book is focused on Naofumi and his party finally taking out Kyo, the maniac with the book of the vassal weapons who has been wreaking havoc on multiple worlds and whose takeover of the Spirit Tortoise back in the world Naofumi was summoned to caused numerous disasters. The previous volume was spent gearing up for the fight, so now it's time to actually get him.

Unfortunately that takes roughly three hundred pages to begin. Most of this novel is taken up with reminders about how things are different here than in the other world the main group came from, as well as last-minute supplying and powering up. In part this is important for how Naofumi is able to use his shield, which retains its powers as a holy weapon despite it not being one of this world's specific weapons. Author Aneko Yusagi spends slightly too long trying to show basic differences between how the holy weapons and the vassal weapons function, both in choosing their wielders and in terms of powering up, and the result is that it feels like we have to slog a bit before we get to the actual meat of the story. Since most of this is done through Naofumi narrating rather than conversations or even using plot to reveal facts, it drags, especially since it feels like a rehash of previous books' similar explanations to a degree.

This technique also limits character interactions severely. While Naofumi does have a much better reputation on this world, and that shows nicely in how he talks with people and in their general reactions to and treatment of him, there isn't much development within the actual party. Raphtalia, who looked like she was finally getting through to Naofumi last book, is very much a background character, and while Rishia gets a few truly impressive moments, she's largely more mentioned than seen in action. The best character development we get is from new player Yomogi, an assassin sent by Kyo to attack Naofumi and his friends at Kizuna's house. Yomogi begins completely brainwashed by Kyo, and through her interactions with Naofumi and her first-hand experiences as the battles escalate, we can see her turn from flunky to avenger over the course of the book. It isn't particularly remarkable because we never really get to know Yomogi as a person – her only known motivation is “Kyo is my friend,” and even her dialogue is remarkably free of descriptions of why she likes him so much.

While it wouldn't be correct to say that the actual fight feels rushed, there's definitely something off about the pacing of this novel in general. From the slog to get to the battle to the fact that it then takes under one hundred pages to resolve it, the book simply feels unbalanced. It's almost as if Yusagi got too wrapped up in world building, because there are a number of details about how the two fantasy worlds compare to each other, as well as monster and magic notes that feel very well thought out. It all simply fails to come together as cohesively as past volumes, which is a shame. Had the world building been balanced with either more plot movement or more character development or interaction, this would have been substantially better.

Despite these failings, the series' core strengths remain. Naofumi has grown a lot as a character, and his initial cynicism and distrust of those around him have largely abated, leaving him in a position to make friends and form warmer relationships with those he has. His concern for the world(s) and the waves that risk their destruction has been steadily growing, and that he's able to appreciate Rishia as an asset to figuring out why they happen speaks volumes about how much he's changed. His primary concern is that other heroes, including those from other worlds, don't seem to understand that this is a real place rather than a game – Naofumi's ability to believe that there are real consequences for his actions remains one of his greatest strengths, and with his increasing people skills, he stands to be able to eventually help (force) others to realize this as well.

With the action moving back to Melromarc and surrounding kingdoms in volume ten, the need to do so is going to increase. The other three holy heroes of that world vanished when they were fighting the Spirit Tortoise, and it's not yet clear whether the fight against Kyo is going to have any effect on that. If they do come back, will they be willing to listen to Naofumi, or will it be more of the same? He's bringing back some texts from Kizuna's world that may help to convince them, but with Rishia the only one currently able to read them, that may risk his credibility, at least with Itsuki, who threw Rishia out of his party. There's definitely something major coming with Naofumi's return, if only because he has so much new information, so hopefully this volume's stumbling will be a minor blip in an otherwise excellent fantasy series.