Kou Ichinomiya, heir to the prestigious Ichinomiya Company has only one mission in life: to not owe a favor to anyone. He's lived that way for 21 years. Until one day when, his pants hung up on top of a bridge, he ends up falling, with the bridge pillar, into the river down below. Nino, a girl who lives under the bridge, saves his life. Kou wants to pay her back, but Nino desires nothing except for a boyfriend; so Kou winds up living in strange community under the bridge with Nino, who also claims to be from Venus, now under the name of Recruit ("Ric" for short).Originally a manga by Hikaru Nakamura, an anime adaptation aired in the spring of 2010, animated by Studio Shaft. A second season, Arakawa Under the Bridge x Bridge (or Arakawa Under the Bridge x 2), aired in the fall of that year. Not to be confused with Hiromu Arakawa, creator of Fullmetal Alchemist, who presumably doesn't live under a bridge, though she may live in a nearby field...
Art Shift — The fifth episode's opening. Even without the apparent rotoscoping, the art has a rather different look.
And every once in a while, Ric shifts into a very shoujo manga look. For example, when he's imagining being Nino's bride (yes, not the other way around), or when he's under "Kameari syndrome" — along with Hoshi and Last Samurai.
Authority Equals Asskicking — Hilariously averted in the case of Mayor, who is highly respected among the riverbank's society with Riku only pointing out he hasn't got any qualifications for this. Also played straight with Sister and invoked by Stella.
Banana Peel — Averted when Kou doesn't even notice that he's walked over them until P-ko points them out. He even goes to point out that nobody slips on them in comedies nowadays. However, it is played straight in the most exaggerated manner shortly after when P-ko steps on a peel and goes on a Slippery Skidforwards and backwards onto more peels before slamming into a wall.
Berserk Button — Calling Kou a leech is the only thing that has managed to make him really rage so far, causing him to slip into a Kansai Regional Accent.
Maria's inability to snark at the guys causes her to snap on poor P-Ko in Episode 7 of Season 2.
Be Yourself — The bridge dwellers seem to center their lives around this rule.
Bitch in Sheep's Clothing — Maria, bonus points for keeping actual sheep in her farm. She doesn't bother too much with hiding it, though, as her looks and warm smile work at people who should know better...
Brainwashed — Kou throughout most of episode 8. Maybe those "tengu" aren't just weird guys in masks.
Butt Monkey — Most of the characters get their share, but Kou as the outsider of the riverbank society and (deliberately) Only Sane Man gets the prize.
P-ko becomes the unfortunate target of Maria's wrath.
Confessional — Between Kou, Hoshi and Sister, though it's closer to an interrogation if anything.
Cool Big Sis — Maria, bordering even at Onee-sama territory, although exclusively for the girls and children. The male part of the riverbank society usually receives a solid portion of bitchiness hidden behind a beautiful smile.
Cross Counter — Between the Mayor and P-ko of all people in Episode 12 of Season 2.
A Day in the Limelight — Last Samurai, Billy and Jacqueline, the only members of the bridge who the audience had not seen at all, get some screentime in the final episode of the first season. Lampshaded, of course.
Debt Detester — The protagonist has always lived by this principle, paying all debts as quickly as possible, but he finds himself in a quandry when a crazy woman who lives under a bridge saves his life.
Do Wrong, Right — When Stella is mercilessly beating up Kou, which she thinks of as a game, Sister steps in...to inform her she can only get a 3-move combo in. Anything else would be overkill.
Does This Remind You of Anything? — Ko's morning narrative in episode 8 talks about two toothbrushes (one blue and one pink) "lining up cozily on the window".
Earworm — The openings and endings of both seasons.
Expressive Hair — Nino's hair sometimes has a life of its own.
Generation Xerox — Ric's dad gets his trousers stolen on top of the bridge, and refuses Nino's help. This time, however, Nino has already retrieved the trousers with her fishing pole, forcing Ric's dad to walk off without them just to avoid a debt.
And later the Tetsujin brothers in episode 10 of season 2.
Human Aliens — Nino, if the Venusian thing is true.
Imagine Spot — Kou is sometimes hitting Hosaka's level with his. Especially wild one occurs in episode 6 of the second season, granted with Naughty Tentacles.
In the Blood — Kou picked up most of his habits from his father. Whenever his father did something for him, he would always make him pay it back.
Jerkass — Hoshi acts like rather petty and visibly ineffectual Jerk Jock from high school and Rival-wannabe towards Riku.
Maria, though she's more of a sadist.
Limited Wardrobe — Nino's jersey, well, under the bridge Hoshi seems to be the only one changing his clothes regularly. Although Sister, Kappa and Riku's cases can be justified, and Ric apparently owns plenty of identical clothing.
Line-of-Sight Name — How the kappa names people. For example, "Nino-san" comes from the 2-3 on the tag of her track outfit (2 is ni, the dash is no, 3 is san).
Maintain The Lie — Kou has told representatives from his company that he's set up a power generator under the bridge and started a new company around it. The problem begins when the representatives come to check on him.
A Man Is Not a Virgin — Well, Kou is. Probably has something to do with his 'I won't owe anything to anyone' obsession...
Masculine Girl, Feminine Boy — When it comes to romance, Kou and Nino to some extent, as she is The Stoic and he has a bit of a shoujo heroine's heart. In chapter 162 / episode 7, Kou has an Imagine Spot with Nino wearing a tuxedo and himself wearing a bridal dress, wondering how it got to that point.
Medium Blending — Every On The Next (and the first preview of the series) has a live-action man in a kappa suit, and, as of Season 2, a man with a star for a head.
Nun Too Holy — Sister, a man in a nun's habit with a large scar who holds Mass at gunpoint. Actually acts pretty close to a nun too, save for the idiosyncrasies.
Only Sane Man — Kou plays this role in the series. However, he can't really be considered "sane" if you consider how far he'll go to avoid debts.
Out of Focus — Although the concept of the series is based around Kou and Nino (they even get actor credits in the opening, which is extremely rare in anime), after the first couple of episodes in the anime, Nino shows up no more often than any of the minor characters. This seems to be just to remind the audience that she exists.
Pair the Spares — Played straight (albeit a bit bizarrely) with Hoshi and Amazoness
Post-Kiss Catatonia — Ko was completely frozen and beet red at first from his First Kiss. The next few scenes he's running and jumping and screaming like crazy.
Power Limiter — The brothers' masks. Although we never see them not wearing them...there's also the scene where they make Kou wear one.
Skepticism Failure — Inverted, at their first meeting, Kou believes, at least for a few minutes, that the man in the green suit is indeed a Kappa.
He comes up with the idea of Hoshi being a star-shaped monster feeding itself with heads of young men to posses their corpses and control it, rather than him being a young man himself and wearing a mask. Arakawa Riverbank's logic's sank into him indeed.
Nino is also one. Kou has a tough time reading her emotions, since her face never changes.
Straight Gay — Underneath that manly suit, Takai's actually very crazy for Ko.
Super OCD — Whitey is obsessed with standing on white lines to the point where he actually lugs around a portable line-maker wherever he goes. It is unknown what happens when he is taken off a white line, but during the Arakawa sumo tournament mini-arc both Sister and Maria withdrew from the finals because they did not want to find out.
Well Done Son Guy — Kou's motivation since his childhood. There's also Kou's secretary, who yearns for Kou to call him father. Kou's real father does not approve ("Papa is still a father, after all"), especially after seeing that body pillow.
With Friends Like These — Maria is considered a valuable member of the bridge community, providing everyone with dairy. She'll also insult anyone at the drop of a hat.