The Master of Ragnarok and Blesser of Einherjar

The Master of Ragnarok and Blesser of Einherjar is a Japanese Fantasy Isekai light novel and manga series written by Seiichi Takayama which began serialization in 2013. It had an anime adaptation in 2018 and is considered to be one of the worst Isekai animes of all time.

Plot
Yūto Suoh is a fourteen-year-old and second-year junior high student who is knowledgeable about urban legends. One night, in his quest to discover if the urban legend of the local Tsukimiya Shrine was true, he irreversibly discovered that the legend was not a sham as he takes the picture of the object. Forcibly separated from his childhood friend and love of his life, Mitsuki Shimoya, Yuuto appeared in another world with heavy similarities to Norse mythology (while doing research on the world, he discovered that the "other world" wasn't truly another world at all, but was an Earth in the distant past, specifically, 2000-1300 BC, the Late Bronze Age). In his quest for survival, Yuuto inadvertently rose to become the patriarch of the Wolf Clan, the family that had taken him in upon his summoning, by using the modern knowledge provided to him by his smartphone that he had unwittingly brought with him to the other world. Despite winning the affections of multiple Einherjars, magic-wielding warrior maidens, Yuuto has but one goal: to return to the side of his childhood friend and one true love (although this does not stop the other girls from trying to win him over).

Why It Neither a Master nor a Blesser

 * 1) Horrendous premise and nonsensical story, with terrible writing to go with it when it comes to ripping off other anime fantasy series or came very rejected:
 * 2) * Also the main protagonist, Yūto Suoh being teleported due to taking a selfie as a means of proving the urban myth's existence is a pretty dumb means of transporting him to the story's main setting.
 * 3) * Speaking of the Urban Legend main sub-plot itself, it just essentially went never mentioned again in the series, after Yūto teleport to Yggdrasil.
 * 4) * In addition, there is not just one horrible plot twist, but four horrible plot twists. The first plot twist reveals that the divine mirror can take you from a modern-day Japanese shrine to assumedly Norse-like Yggdrasil. But, later on, in the series, it's revealed that the setting's appearance is actually but weirdly pseudo-ancient Egyptian with Norse elements, and their location is on Earth, but in the distant past, thus making the Isekai trope just as more pointless and should rather calling this as time travel. Also, not only is Yūto's phone from his time period, but it somehow works and the battery is somehow not dead yet, despite Yūto being stuck there for two years now.
 * 5) Plot hole: How did Mitsuki steal the divine mirror as means to communicate with Yūto without getting into trouble with either the owner (or priest) of that shrine where the mirror resides or her parent(s), as the only time to see her again is at her room with the mirror in a couple of episodes, before switching it with her smartphone.
 * 6) Despite the light novel portraying Mitsuki as the story's female deuteragonist, in the anime, however, her role was reduced to a bland supporting/important minor character and instead, this role was given to Yūto's sworn "younger sister" and "daughter", Felicia and Sigrun (thus making the latter as the anime's tritagonist), respectively.
 * 7) Very stupid title. It sounded like the creator came up with two titles and coul
 * 8) All the characters in the anime are about as cliché, just like in the manga, each member of the female harem relentlessly lusts after Yūto. Even their character designs are cliche with over-exaggerated female proportions, and three of them are underage and one is a slave that Yūto bought. It also doesn't help that they're referred to as his "sisters" and "daughters", which might have some historical reasons (the only point where it's even a tiny bit accurate, spoiler alert), but makes it much more uncomfortable to think about considering they all want to have sex with him. It seriously makes Sword Art Online's harem seem less egregious by comparison.
 * 9) Speaking of Yūto, Yūto is a very boring character. He literally has no personality traits besides being way too modest to the point where he doesn't take credit for his achievements (which every member of the harem literally mentions constantly), making him just about the most blatant Marty/Gary Sue in media.
 * 10) It doesn't even make sense why they tried to use Norse mythology in that world. First off, it takes place somewhere around 2000-1300 B.C., long before any such mythology would've existed, and it looks more like ancient Egypt than anything even resembling the Viking world, for anybody expecting as much.
 * 11) The technology is also way too advanced, with ancient Rome-like chariots and katanas (the latter of which is literally just there to appeal to the Japanese fans), to be anywhere near the time period, thus making the anime's setting generally more semi-historical sci-fantasy than typical Isekai fantasy, but very badly executed.
 * 12) The artwork and animation are absolutely abysmal, looking like something from the early 2000s. Heck, It looks more like a Newgrounds animation than an official one, which is unacceptable since this anime came out in 2018. Most animated scenes consist of reused animation, and some scenes even use static images. This was probably done because some scenes were likely too hard to animate and it looks like their budget ran out because of it.
 * 13) Extremely lackluster direction that cuts corners with animation, like having a character's face in a profile view to simplify it which just looks stupid and awful.
 * 14) The god awful opening with the terribly animated fight scene. First off, how is that guy swinging the hammer like that? That hammer clearly has no weight put into it at all. It looks so bad that it almost looks like a fan animation. The same exact fight scene in the episode from the opening is even worse.
 * 15) Constant ecchi scenes that are super contrived and uncomfortable to watch. They play no part whatsoever in the story and only serve to pad it out, especially considering that nothing ever happens in any of them since Yūto is devoted to being "faithful" to his one true "love" in the real world, Mitsuki (who's even more boring than the rest of the harem), and these ecchi scenes happen without his consent while there are literal children around. It is, as Mother's Basement says, "a bit of a mood killer".
 * 16) Awful fight and battle scenes that have no creative choreography whatsoever and are pretty much just people flailing their bodies erratically until something happens, and they're all over way too quickly.
 * 17) Even the name of the world has been used constantly in and out of anime. Or, as Mother's Basement would say, once again, "Cause if you're gonna give up, you may as well give up all the way".
 * 18) For some reason, this anime feels more like a second season than a first season. Since a second season of an Isekai anime would make the main character go to another world, it makes this anime feel like they skipped a bunch of arcs from the manga and just went to do a timeskip for no reason. Yes, there is literally a timeskip right after Yūto goes to the "new world", taking place two years later when he's become the leader of the Wolf Clan. Yes, it literally skips over anything even remotely interesting that could happen in favor of showing the harem.
 * 19) All in all, the series contains just about every single anime cliché from the book and no subtlety about any of it.

Redeeming Qualities

 * 1) The music is pretty nice to listen to at times.
 * 2) Good voice acting in Japanese and English dubs.

Reception

 * The anime adaption has been considered to be one of the worst animes of all time for many of the above reasons along with it's terrible animation, direction, and sound design. It currenty holds a 5.7/10 on Myanimelist.com.

Videos
https://www.youtube.com/watch?v=2dAIvjuj1dg&t=509s