Currently, hundred of different alien species come and go, living their lives on the Earth. Species that come in peace, aggressive warlike species... Aliens with all kinds of personalities live among us, maintaining a precarious balance.
— Opening Narration
Contrary to the belief of its native inhabitants, Mankind isn't the only sentient species living on Earth. Actually, individuals of about five hundred alien species call Earth home for reasons as diverse as their biological peculiarities. The Diskun and Erald, for example, come to Earth because Humans Are Special to them; others are refugees, like the cursed inhabitants of the dead planet Conwell; some come looking for love, like the future Mucbak Queen; and not everyone has a choice on the matter, like one of the last mermaids of Horn. Their existance is a secret to the average human citizen; however, with so many aliens around, it's inevitable some humans eventually get tangled in their bizarre stories. These humans are said to have entered the Level E.Level E is one of the least known works of Yoshihiro Togashi, of Yu Yu Hakusho and Hunter × Hunter fame. Prone to Art Shift, Genre Shift and Mood Whiplash, it can go from a wacky parody of Pretty Freeloader shows to a tragic Horror story without missing a beat, and it lacks a definite protagonist, having an Ensemble Cast whose most recurring character is a certain Prince from the planet Dogra.An 13-episodes Anime adaptation by Studio Pierrot aired in 2011.
Aliens Are Bastards — Some species are said to have exterminated others for the pettiestof reasons. And individuals don't fare better, acting as ruthless, greedy and fanatical as the worst of humans.
Did Not Do the Research — Togashi named this series Level E because he thought alien starts with an e in English. He associated it with extraterrestrial.
Probably doesn't help that when 'alien' is transliterated into rōmaji, it becomes 'eiriyen'. Or something like that. Point is, it starts with an E.
Did You Just Romance Cthulhu? — Kyoko doesn't realize what that cute foreign girl is and what dire consequences dating her might have for Mankind.
Heroic Comedic Sociopath — The Prince does try to help the Earth... while having fun (from his point of view).
Honor Before Reason — Kyoko won't date lesbians; she wants girls to love her as if she were a guy, hoping to eventually find someone who feels If It's You, It's Okay for him/her.
Hot Blooded — Hotheads Yukitaka and Captain Kraft. The former gets hypertension from the Prince's wacky antics. The latter, well... he's just irritable.
Humans Are Special — For the Diskun and Eralds, humans are off limits. Who knows which human might be a potential baseball star or parent to one?. The Mucbaks think humans have great genetic potential.
Inferred Holocaust: Subverted. After Yukitaka accidentally blows up the Prince's ship, a clip show plays of the funerals of those caught in the blast. Double subverted when it turns out that there were no casualties, much to Yukitaka's relief.
Kid Hero: Both lampshaded and subverted in one of the stories. The kids who the Prince dragged into one of his crazy anti-boredom schemes completely called him out on actually picking kids to fight monsters. They eventually go along with it kicking and screaming, sometimes literally.
Mood Whiplash: Constantly. This show can and does transition from dramatic to tense to comedic in the span of about 60 seconds, all with the same characters.
Older than They Look — The kids are in 5th grade (11-12 years old) and Yokota already has a tween Perma Stubble, but Shimizu and Mayuzumi look younger than their grade suggests.
Oh, Crap! — ...is not enough to describe the look on Kraft's face, when he thought that his Prince killed a Disconian.
"Clive from the planet Jacqueline Ess" is a reference to the Books of Blood. Come to think of it, the whole series might have been inspired by that famous horror anthology, given the episodic structure, some of the themes explored, the black humour and occasional forays into the weird and macabre.
Sour Supporter — Kraft, who has been a bodyguard for the Prince for ten years, hates his guts intensely but keeps protecting him solely out of loyalty to the King and Queen of Dogra.
Troll — The Prince is currently in competition with Izaya for the ultimate fictional troll title.
The Prince isn't the only troll, in fact, the entire show trolls its viewers.
Twist Ending — What do you know, humans aren't the only sentient beings native to Earth. Good news for a certain Woobie mermaid.
Regarding the Conwell story: Apparently, the entire arc was just Prince Baka pitching a story to an executive which gets rejected for being too dark. Even though the Prince suggests that the Conwell aliens exist, it's hard to know if he's telling the truth knowing his usual habits.
Uncanny Valley — All the "inhabitants" of Calvary live deeply in it.
All Just A Story — The fourth episode, which was just one of the Prince's attempts to convince humans that aliens exist.
Amusing Injuries — I mean, come on, people! Yukitaka punished Prince with a reverse roundhouse kick, Slo Mo and all!
Not to mention Captain Kraft doing the same thing only with a Repeat Cut and then throwing the prince in the air, kicking him multiple times while falling and ending with a piledriver.
And later Shimizu gives him a Megaton Punch followed by him and Momochi using the king as a hammer.
Bait-and-Switch Credits — The OP presents the series as an actioner with a blonde alien bishie hunting uglier aliens.
Pragmatic Adaptation — The animated version adds fanservice and action sequences to some arcs and removes some scenes from other in order to make them fit into the tv episodes.
The Stinger: After the end credits of the final episode, it is revealed that the cat was a spy all along.
The Unmasqued World — At the end of the anime, Prince was outwitted and married the princess of Magura, removing under observation status from Earth - and revealing the entire alien armada to the entire planet.