In one manga chapter there was a pseudo-sportive competition between the classes of Tomobiki High, and Ran protested that one class had a crushing physical advantage over the others. Given the nature of the competition and the experience the students have on them, Ataru's outrageous speed, Lum's ability to fly and Mendo's arm strength weren't crushing... Then an episode showed that one of their classmates is Fist of the North Star's Kenshiro. Who is faster than Ataru, stronger than Mendo, and already knows how everyone moves. Ran was protesting his presence. And the headmaster missed him (thus explaining how easily his class won).
When Kenshiro fought Kotatsu Neko he didn't use any of his trademark pressure point techniques, but has two good reasons: first, Kotatsu Neko is a cat and a yokai, and it's unlikely Hokuto Shinken, designed to be used on living humans, has pressure point techniques that work on them; and second, even if Hokuto Shinken did have pressure point techniques for use against cat yokais (something entirely plausible, given the number of extremely specific techniques Kenshiro has shown in his own anime), as a high schooler he's neither the successor nor the heir, so he's forbidden to use them outside training. Thus he instead resorted to the Hokuto Senju Satsu... And lost miserably.
Rei is never seen without his rocket pack—other Oni can fly but he can't (possibly as a side effect of his bovine lycanthropy) so it's equivalent to a human using a wheelchair. When Ataru gloats over getting to fly the school's light aircraft, Jariten thinks it's ludicrous that someone would be proud of needing to use a machine just to fly.
Many (in and out of universe) have wondered why Lum puts up with Ataru. The explanation is easy, and indirectly provided by Ataru himself: because he put up with her back when she ruined his chance at marriage, forced her way in his home, ruined his relationship with his girlfriend, and started zapping him if he did as much as look flirty with another girl. Not only that, but when he had a perfect chance to send her back to her planet with Rei (Lum promising she would get back with him if he could say an entire phrase in Japanese, something he did by reading it) he wasted it (he, along the Stormtroopers, denied that Rei had completed his challenge) because Lum was that desperate to not get back with him. Considering this, Lum being a Love Martyr makes a lot more sense.
Also, Lum and Ataru aren't really that different. Despite Ataru being a womanizer and Lum having Ataru as a single target, Lum has shown herself as being able to be as much a slob as Ataru, that if Ataru ever let her she'd happily indulge in every carnal desire towards him running in her teenaged mind. And, if the past counts, romancing the good looking but very simple minded Rei is something Ataru would have done in her shoes. They just both won't ever admit what a perfect fit they are to each other.
Lum is shown to be extremely possessive of her iconic tiger-striped bikini, going to great lengths to get it back whenever it's stolen. Even when otherwise wearing human clothing, she still uses the bikini as underwear. The introduction of Shingo hints why; attempting to repel the electricity-resistant boy, Lum generates a much stronger shock than usual, with the unfortunate effect of burning and vaporizing her clothing — except for said bikini, which is unharmed. The alien fabric is obviously conceived to be resistant to her powers; if she were to use them while wearing normal underwear, she'd risk ending up naked from letting out a too strong discharge.
One of Lum's devices determined that Ataru and Mendo are just as stupid as each other. Considering that it happened after Ataru started giving up on acting civilized due how little respect he got for saving the world and the messes Lum got in, plus Mendo's own high education, it doesn't speak well of the latter's qualities. No wonder Lum decided to stay with Ataru: if Mendo, with all his advantages over him, was still only Ataru's equal, she had no reason to dump her beloved boyfriend.
This could be at least part of why, in episode 93, Sakurambo, who often decries Ataru's vices and bad karma, still declares him a better man than Mendo.
This may also be why Kurama flat out dumped Mendo after discovering his fear of the dark while he tried to help Ataru with his apparent lack of manliness: as far she was concerned Ataru only needed a good example (and gave up when even exposing him to Ushiwakamaru failed), while Mendo, being from a wealthy family, should already have them.
Sakurambo's appearance may be based on a yokai called the Abura Sumashi, which appears as a small man wearing a traditional straw raincoat (a common outfit of Cherry's) with a disproportionately large head and extremely ugly features, which meshes well with the Running Gag the series has of suddenly doing an extreme close-up of Cherry's face, which causes the other characters to react with disgust and horror.
Ataru gets no respect in spite of saving the world in the very first chapter/episode, but there's actually a good reason for it... Namely, resentment:
In the manga and original anime, the Stormtroopers talk Ataru into an attempt at psychically summoning Lum, resulting in an alien taxi bringing them home and demanding a payment of value equivalent to Earth's entire oil reserves... And when Ataru obviously refuses, he and his colleagues start stealing it, and his involvement is leaked on TV (while the Stormtroopers aren't mentioned). Lum arrives to save the day and pay the bill in exchange for Ataru letting her live with him, and Ataru refuses until he's beaten up by the Stormtroopers and all the others... And when they're paid by Lum, the alien taxi drivers give back the oil by making it rain. The entire situation eroded any good will he had for his heroics and then some, especially as he was told how he could stop the oil theft and refused until forced.
In the All Stars anime Lum just moves in... But his attempts at calling Shinobu on the phone and Lum's jealous interference cause the disappearance of a plane and a helicopter, and when he just goes out to meet Shinobu in person Lum unleashes a lightning storm that devastates the neighbourhood. Ataru is blamed for that, especially as his Accidental Proposal to Lum is public and only he, Shinobu, Kosuke and Kakugari know that he was talking of how he'd marry Shinobu so it's believed he was cheating on Lum and caused the entire mess because he couldn't stay faithful.
The latter incident, that was also present in the original, explains why Ataru's parents are emotionally abusive: they had to pay for the entire damage, and while they somehow managed to stay afloat they still got stuck with the debt from something Ataru is partially responsible for.
Lum is especially close to Benten compared to her other childhood friends because she's the one who causes her the least trouble: Ran had already developed a split personality and her crush with Rei, making them drift apart, Oyuki is normally calm and graceful but also cold, calculative, and had absolutely no issue with having sex with Ataru when he jumped her, and Benten at her worst is just hypercompetitive on Setsubun (where she flirted with Ataru to trick Lum into leaving the basket she was supposed to keep steady).
Also, despite her tomboyish tendencies, Benten is often the "Voice of Reason" of their childhood group.
The Moroboshi home tends to get wrecked a lot in the anime (less so in the manga) and then snap back to normal. But remember that Lum is both very wealthy (casually paying off that ruinous space taxi debt) and has a lot of handy alien gizmos; she probably rebuilds it herself whenever it gets ruined.
That does raise the question of why Ataru's dad worries about the mortgage so much, but remember that Lum's an alien with an imperfect understanding of Earth culture; she may not know what a mortage is, so unless her father-in-law asks her to help him pay it off, she has no reason to do so.
In Lum's little group of alien cuties, three of them are easily recognizable as being aliens based on Japanese yokai; Lum herself is an oni, Oyuki is a yukionna, and Benten is based on the goddess of luck of the same name. The only one who doesn't immediately strike an apparent mythical chord is Ran, which leads to either of two realizations.
Firstly, Ran's Cute Little Fangs and life-sapping kiss call to mind either a vampire or a succubus — both Western monsters, in contrast to the Japanese trio. This further symbolizes her status as the "internal outsider" of the group — Lum wants to think of Ran as her friend, but is forced to keep her at bay due to Ran's own vendetta and scheming, whilst Oyuki and Benten have openly grown away from her.
Secondly, if you look closer into Japanese mythology, there is a yokai that Ran resembles; the Hannya. This is an oni-like she-demon, created when a human woman allows herself to be consumed by jealousy, which steadily twists her into a monster. They're considered a subtype of kijo, a she-demon counterpart to the oni, and are feared for their use of Black Magic and subterfuge to carry out their thirst for vengeance against those who have wronged them. This meshes with Ran's close ties to Lum, the fact that she's an antagonist due to her being consumed by her wrath over Lum's many petty crimes against her and her jealousy of Rei loving Lum instead of her, and her reliance on indirect schemes and trickery to try and get back at Lum.
Megane's political ramblings in the 1981 anime are rather weird, combining some very obvious Communist rhetoric about "workers rising up" and "opposing the bourgeois" with rants about the modern Japanese abandoning the traditions and culture of their ancestors; Communism tends to be somewhat opposed to such nationalistic attitudes. Then the brilliance hits; another popular term for Communist philosophies is Socialist. He's a Nationalist and a Socialist... or a National Socialist. Keep in mind, Megane is the one who named Lum's fanboys as "Lum's Stormtroopers", he's been seen doing a Nazi salute, and he even tries to set up a Nazi-themed cafe in the 2nd movie...
Oyuki tried to seduce him before getting to know him... And after Lum spent some time with her a few days after Ataru helped her fending off Rei. She likely had heard her friend gushing over Ataru and complain about his perversion for days, and that made an impression.
Benten flirted with Ataru on their first encounter. She's also Lum's best friend, and had heard everything about him. It's only after that she sees how much of a pervert he is... And still gives him some respect.
Ryoko pretends to want to marry Ataru almost as much as she does with Tobimaru, but is far less horrid with him. As she witnessed his qualities from the start, she may actually hold (slight) romantic feelings for him - if anything she actually let him act perverted once.
Even the women that aren't romantically attracted to Ataru give him some respect after they get to know him: Kurama treats him (slightly) better than Mendo after seeing them act almost identically but with Ataru being at a clear socioeconomic disadvantage and not scared by darkness and closed spaces, Sakura does the same because Ataru unwittingly saved her life when they first met and never held against her how much he suffered in the processnote At the time Sakura suffered from a very poor health due being haunted by an enormous number of yokai that is implied would have eventually killed her... Had she not accidentally sent them all to haunt Ataru but his perversion infuriates her, and Ryunosuke somewhat trusts his advice after seeing him go out of his way to give her a sailor uniform and taking out her father.
Fridge Mythology Gag: when Ataru accidentally travels ten years forward in time in the All Stars anime, he initially mistakes Kokeru Moroboshi for a Zashiki Warashi... That is the same kind of yokai that in the manga Kurama initially mistook his mother Shinobu for.
The accidental time travel may be responsible for Ataru and Lum eventually getting together: Lum was horrified when she found out Ataru's son wasn't hers and Ataru even more when his son's stupidity made it look he had married an ugly woman, and would have scared them into actually communicate... Thus avoiding the eventual break-up they had in that timeline.
Actually confirmed for the All Star anime: they immediately start thinking how to prevent that future, and the episode's end shows Inaba and the Fate Production Bureau.
Fridge Horror
What will happen when Ryuunosuke starts her periods, if she hasn't already? Her dad certainly won't help her with that, since he's stuck in his delusions.
Then again, she's good friends with Benten, so she probably helps Ryuunosuke with that.
She could ask Benten, Lum, Shinobu, and even Ataru and Mendo (though she'd never do with the last two).
A disturbingly high number of the parental figures in this series are Abusive Parents when you think about it:
Ataru's parents are emotionally abusive, with his own mother's catchphrase being variants of "I wish I never had him", and both of them confessing they would have rather had a girl. In the Viz Media translation of the manga, in one chapter, an eagle-eyed reader will spot that the photo album of Ataru's childhood is literally labled "regrets".
Ran's mother subjected her to so much verbal and physical abuse in the name of corporal punishment that Ran become borderline psychotic herself, desperately striving to cover up her spiteful, vindictive true-self with a desperate kawaiiko persona to the point she almost seems like a borderline split personality.
Ryuunosuke's father Wanted a Son Instead and has subjected Ryuunosuke to a life of verbal and physical abuse, berating and beating her in an effort to make her a "man among men". On top of that, he has also kept her impoverished throughout her life to keep her from buying feminine clothing, has repeatedly starved her due to selfishiness and his own poor business skills, and has repeatedly gaslit her either to keep her under his control or so he wouldn't have to share treats like chocolate or matsutake mushrooms with her.
Ten's parents were extremely neglectful, abandoning him to the care of robot nannies so they could focus on work, which doubtlessly contributed to his growing up to be such a Spoiled Brat. His mother, the only one of Ten's parents we meet in canon, is literally addicted to fighting fires. She's also been terrifying Ten with graphically gruesome stories of the things she does to "pyros" (people found to have set fires on purpose) since he was a baby. In her defense, she's probably the least-worst parent on this list, since she genuinely loves Ten and simply never realized her stories scared him... also, part of Ten's reason for being scared of her is because he's a Spoiled Brat who abuses his fiery Breath Weapon, and he knows she'd take a very dim view of this if she found out.
For the human parents, their neuroses may stem from the fact that, being in about their 40s in the early to mid-'80s, they would've been born before or during World War II, with the heavy bombings and postwar deprivation incurring some PTSD. (Ataru's dad seems particularly shell-shocked at times.) It might have been even worse for Onsen-Mark and the Cloud Cuckoo Lander Principal, who seem to be older and thus would have much more vivid memories of the war and bombing (the Principal in particular looks to be in about his 60s, which may mean he was old enough to actually fight).
In a similar vein to the prospect of the Earthling adults likely having experienced the horrors of World War 2, Ataru and the rest of his teenage fellows might about decade later have been negatively impacted by the 1991 crash of the Japanese economy, from which Japan's economy has still not fully recovered. If you consider 1978 (when the manga started) or 1981 (when the anime started) as a "Year 0" for the series timeline, they might've been twentysomethings trying to raise families at the time; if you set it more around 1987-88 (when the manga ended and the Final Chapter movie was released), they might've been just graduating from college or starting out in the workforce at the time. People just starting out in life during the 2008 Great Recession or the COVID-19Pandemic can relate.
Every myth in history is caused by advanced aliens coming to Earth to frolic becoming part of our legends as gods and demons. While the Oni are shown as graceful conquerors willing to let Earth people keep their freedom after Ataru's win and even letting their princess and her friends stay, Earth is still one of the least space aware populations in an entire universe of advanced aliens with stronger physical attributes able to wage war on a whim.
Ataru's behavior at the end of the 1983 anime episode "And Then There Was None" (episode 83) is supposed to be part of the joke and Status Quo Is God, but could easily have a darker interpretation: Ataru just saw all his friends and his wife die over the course of the last week. Ataru could be flinging himself into his old flirtatious ways as an effort to distract himself from the guilt and pain, in effect Drowning My Sorrows, but with skirt-chasing.
The Reveal that the Serial Killer had Ataru's face is actually something Ataru could easily believe as being true; thanks to his Weirdness Magnet status, Ataru knows that there's all kinds of monsters and super-science out there — he's met shapeshifters and been cloned. There really could be an Evil Twin of Ataru out there, or a shapeshifting Serial Killer, and Ataru knows it.
Fridge Logic
The plot of the 1983 anime episode "And Then There Was None" (episode 83) has two rather major plot holes when you stop and think about it:
Firstly, why was Lum's participating unintentional? Everybody involved knows that Lum is utterly devoted to Ataru, and also that she's possessive as all hell. If you invite Ataru somewhere, Lum's coming with him is virtually a certainty.
Secondly, the whole point of this gaslighting project was to basically shock Ataru out of his Loveable Sex Maniac behavior. But no effort is actually made to correlate the deaths and Ataru's lechery at all. Ataru is actually on very good behavior before the killings start, and once they start, he has no lechery on his mind at all. Ataru has literally no reason to even subconciously attribute the deaths to his being a wannabe-playboy; from his perspective, he just went to a holiday vacation and got attacked by a sadistic Serial Killer.
