Whether or not this 12-episode light novel adaptation should properly be called an isekai series is a matter of some debate, as it may instead actually be a time travel tale. However, its structure and virtually all of its other characteristics are consistent with isekai stories, so it may as well be considered one even if it technically isn't. Besides, the series has much bigger issues that are much more worthy of commentary.

The series did not fare well enough during its Summer 2018 debut to make the weekly review list, with its first episode earning weak critical and fan responses. (I gave it a 2 out of 5 myself.) Unfortunately the pass the series was given on polling was also merited by content beyond the first episode, as the series has a lot of problems. The single biggest one is that the series does not actually start at the beginning of the story, and the details about how things got to the point where the first episode starts only sporadically show up in flashbacks, if at all. In fact, I spent much of my time watching the series wondering if there was some first part or prequel that I missed, but no, this is the only animation that the source material has earned to date. How Yuto even got to Yggdrasil is suggested by the opener but never actually fully explained until a very brief account in the last episode, and the text in the eye catches provides much more detail about what happened in the two years between Yuto's arrival and the start of the series than what the episode content ever does.

Then there's the matter of the setting. Numerous Norse names are tossed around, but why there would be Nordic themes in an early Iron Age setting which, based on terrain and architecture, looks like something from the Middle East is never explained; if it is merely the original author's whim, it makes for an incongruous marriage of cultural traits. What the deal is with the runes that the Einherjar bear, including why they have them, where they come from, and what special responsibilities they assign to their bearers, is also never even much hinted at, much less explained. The political and territorial situations are also only vaguely described and a map is never provided. Taken collectively, this amounts to either tremendously lax world-building on the part of the original author or else a major oversight by director Kōsuke Kobayashi and his adaptation team.

To an extent the approach taken is understandable: the creative team did not want to waste time with little details and instead wanted to get to the (comparative) meat of the content immediately. In this case that means throwing out lots of cute or sexy girls, setting up situations for them to fawn over Yuto and be beholden to him, and throwing in some battles which Yuto can master by using the “cheats” of info from his phone to outclass opponents with knowledge that is revolutionary for the time period. (At least he does admit on multiple occasions that they are cheats.) To foster the harem aspect, the story even goes as far as having leaders be Patriarchs and those under him being sworn “little sisters” or “daughters,” just in case the arrangement was too subtle. Granted, a leader being referred to as a Patriarch or something equivalent is hardly a novelty to this series or anime in general, but it cannot be divorced from blatant otaku pandering here. While this is a case where the protagonist only has eyes for exactly one girl, and thus carefully avoids situations that are too compromising with others, the way various female characters either try to seduce him or (in one case) service him out of a sense of duty still keeps the harem aspect alive. The one bizarre twist on this aspect is that when the series' one actual (and fully gratuitous) sex scene does finally happen, it does not involve Yuto or any of the harem girls but instead a different couple entirely.

The series is also unlikely to win any viewers solely on the basis of its technical merits. Everything about the visuals comes up as either uninspired or mediocre in execution, and usually both labels apply. The girls present at least some variety in physical types, though more petite builds are favored, and the only one which stands out as especially sexy is one sultry antagonist. Otherwise designs are run-of-the-mill for dating sim-caliber artistry. The actual depictions of characters, settings, and equipment are all mediocre at best, and the animation, though not exactly bad, is more commonly than not a disappointment, with battle scenes rarely being interesting despite some face-offs which should have potential. Even the fan service outside of the sex scene is lackluster, with the raciest content mostly relegated to the closer. Decent fan service can buoy up weaker content elsewhere, but this series cannot even offer enough on that front.

The series does a little better with its mostly-orchestrated musical score, especially in some dramatic parts near the end. However, even then it does not stand out much. Cheery opener “Bright way” is more notable for the information it provides about how Yuto ended up in the other world than for its generic J-pop sound, while the perky, cutesy closer is also much more notable for its visuals, in this case the biggest chunk of the series' fan service.

Funimation's release of the title comes on Blu-Ray only with accompanying rights to a digital copy. On-disk Extras include clean opener and close, a promo video, and translations of all of the eye catches. (They are not translated in the episode content.) It also includes the English dub, which is mostly capable but also mostly unremarkable; the only performance which stands out in a good way is Kate Bristol's sly take on Christina, the elder of the two twin princesses, while on the bad side Lara Woodhull comes across as just a little shrill as Mitsuki. The English script at times strays quite a bit from the subtitles but rarely enough to change essential meaning.

The end of the series presents some strong points, such as how the relationship between Yuto and Mitsuki takes a big leap forward, but it is also sloppy in how it rushes the very end and glosses over things going on in Yggdrasil when Yuto pops back to his world/time. Given that there are 19 light novels as of this review's publication time, there is definitely a lot more story which could be animated, but I am not convinced that any more would be worth animating even if the series was made better. Where it stops is about as good a note to stop on as a series with such limited merits could hope for.