Tensei shitara Slime Datta Ken Movie: Guren no Kizuna-hen

tl;dr: A pretty generic filler film that’s decent enough.

This is a filler film that takes place after the second season of Tensura. As is generally the case with filler films, most everything it introduces will never be seen again after this film. Surprisingly, there was a pretty major exception to that in that this film is the anime debut of Violet, a character that’s pretty important. And I guess this film also somewhat fleshed out Diablo in ways that hadn’t been gone into in the anime yet. However, at the end of the day, the writing has to be careful not to do anything that ... will have any impact on the overarching story so it’s not like it did all that much with them.

Tensura is at it’s best when it’s combining lots of intricate plot lines and world building so not being able to actually do anything impactful long term is especially hindering as compared to filler films for other anime like battle shounen. Still, I suppose the plot was pretty good within the scope of what it could do. It was pretty simple, straightforward, and somewhat generic, but it was reasonably enjoyable.

It didn’t really do much with any of the main cast other than reinforce some character beats a bit, but it did a pretty good job with the two new characters Hiiro and Towa. They don’t really get character arcs either, but how self-sacrificing they are is enough to hold up their character for the span of a film and build up enough investment in them to give the emotional beats in the finale some weight. Though I feel it would have been better to make their relationship more clearly romantic to add a bit more spice to things.

The art and animation for the most part were a bit better than the main series, but not dramatically so. The exception to that was the action which was noticeably much better. None of the new character’s designs really stood out that much, and I feel it was a waste not giving everyone new outfits like filler films often do. The soundtrack was decent enough but not particularly memorable. The ED was the standard film white scrolling text on a black background, but the song was pretty good.

This movie bucks the recent trend of popular anime having in canon movies. The likes of Kimetsu No Yaiba and Jujutsu Kaisen have cinematic releases that continue the story from the seasonal releases.

Before this spate of movies, it has been original stories for movies, something the Dragonball franchise is familiar with, given the multitude of releases through the years.

As an original story by the original author, it fits into the continuity of the anime series which has already multiple seasons and a spin-off, since that story continues to air and expects sequels.

However, the light novel series that has served as the source material of ... the franchise has already concluded and thus lessens the impact of this story on the overall narrative.

This story is canon, but anime only. As for the movie itself, it scratches an itch while waiting for the next Slime Isekai season. The animation looks marginally better than the seasonal anime, but ultimately this is just a side story.

Even after excusing all the strange things from the main series presented as normal to the potential first-time viewer, you have a movie that drags on forever, has far too many characters, mind-numbing dialogue, diuretic pacing, terrible color grading, brainless audio balancing, a generic artstyle, and the same mediocre TV quality digital animation that you'd expect from any schlocky seasonal isekai, and not from a feature-length movie that people were expected to pay money to see in theaters.
 
Bottom line: This isn't fun to watch. It's not "so bad it's good". It's not a dumb but entertaining action flick. It's, at best, easy to fall ... asleep to, and at worst, an annoying reminder that there's an incredibly large audience of people who deliberately choose to dedicate a startling amount of their unpaid attention and time on this earth bankrolling thoughtless media that fails to be fun on even a superficial "keys jingling in your face" level such as this. Watching this movie is like watching paint dry. Low quality badly mixed paint.