A 16-year-old girl who is allegedly the older of the duo. She is depicted as a peppy, optimistic, and cute girl.
- Anime Accent Absence: Though to be fair, she's being voiced by Janice Kawaye (who's Japanese-American), who knows how to speak Japanese.
- Asian Airhead: She's Japanese and not very bright.
- Author Avatar: When asked if the real Ami is anything like her cartoon counterpart, the real Yumi said "Yes, she is".
- Balloon Belly: She's shown as this in "Taffy Trouble" and "Rock N Roe".
- Berserk Button: Ami gets annoyed when Julie mistakenly calls her Arthur.
- Beware the Nice Ones: Happens to her sometimes. One example would be in "Collect All 5!".
- Cry Cute: When she gets very upset.
- Curtains Match the Window: Her eyes are pink like her hair.
- The Cutie: Just look at her, she's just as cute as a button!
- The Ditz: She's often portrayed as the least intelligent of the group.
- Flower in Her Hair: She wears a flower in her hair.
- Friend to All Living Things: She adores animals.
- Genki Girl: She's a very cheerful and exciteable girl.
- Girlish Pigtails: She has pigtails as Pom Pom in "Team Teen".
- Girly Girl: She has a fondness for stereotypically girly things.
- Handy Feet: Playing the drums, as shown in "Ami Goes Bad" and "Mean Machine".
- Heterosexual Life-Partners: She and Yumi are close friends who happen to be the same gender.
- Idol Singer: She and Yumi are teenage singers who are widely popular, especially in their home country of Japan.
- Kawaiiko: She's so adorable!
- Kiddie Kid: She acts stereotypically childish sometimes, mainly in her infatuation with cute things.
- Kindhearted Simpleton: She may not be the sharpest tool in the shed, but good lord is she a sweetheart.
- My Nayme Is: Ami (Ah-mi) is often mispronounced as Amy (Ey-mi) in promotions and discussion.
- Neat Freak: This was even brought Up to Eleven in "Neat Freak", to the point where she was obsessed with cleanliness.
- Nice Girl: The friendliest of the pair.
- Odango Hair: She has these to complement her wavy pink hair.
- Phoneaholic Teenager: She is canonically 16 and is shown to be addicted to using the phone in "Number, Please".
- Pink Means Feminine: She has pink eyes, pink hairs, and wears a pink skirt.
- The Pollyanna: She's willing to look on the bright side of things (even when there might be none) and tries to find a solution to every situation (the keyword being tries).
- Rapunzel Hair: Her hair is rather long.
- Rose-Haired Sweetie: She has pink hair and is very sweet.
- Tomboy and Girly Girl: The Girly Girl to Yumi's Tomboy.
- You Gotta Have Blue Hair: Or pink hair in Ami's case.
- Zettai Ryouiki: Her legs are bare between her boots and her skirt.
A 16-year-old girl who is allegedly younger of the duo. She is depicted as a cynical, sarcastic punk rocker.
- Adorkable: Especially when she can talk to squirrels.
- Anime Accent Absence: She does not speak with a Japanese accent.
- Author Avatar: Subverted; when asked if the real Yumi is anything like her cartoon counterpart the real Ami said "No, she is not".
- Balloon Belly: She's shown as this in "Taffy Trouble" and "Rock N Roe".
- Big Eater: "Chow Down" had her eat a whole lot of hotdogs and several metal horse shoes. However, she can only eat large amounts when she's extremely bored.
- Cloudcuckoolander's Minder: She's the voice of reason for Ami.
- Curtains Match the Window: Her eyes are purple like her hair.
- Cute Little Fangs: Mostly off-screen and moreso in promotional images.
- Deadpan Snarker: She tends to make sarcastic quips.
- Expressive Shirt: The skull on her t-shirt tends to shift expression to match her own.
- Goth: Though she is more of the "I Love MCR" than the "I Recite Deep Depressing Poetry" variety.
- Grumpy Bear: She's a sardonic character in a lighthearted show.
- Hair-Trigger Temper: When she's in a bad mood, she tends to get very furious at the drop of a hat.
- Heterosexual Life-Partners: She and Ami are close friends of the same gender.
- Hidden Depths: She's able to talk to squirrels.
- Idol Singer: She and Ami are teenage singers who are very popular, especially in Japan.
- It's All About Me: Sometimes she comes off as only caring about herself. Episodes like "Hungry Yumi" (where she forces a sleep-deprived Ami to get her a Pink Palace cheeseburger and ends up resorting to stealing someone else's burger) and "Movie Madness" (where she hogs the credit and stardom of being in a movie and doesn't give Ami her due credit) would be the best examples of her selfishness.
- Jerk with a Heart of Gold: She may be sarcastic, grumpy, selfish and violent at times, but she's a Nice Girl at heart and cares a lot about the people she knows (yes, this includes Kaz).
- The Lad-ette: As a G-rated example. She enjoys ninjas, monster trucks, car crushers, R-rated action movies, and anything else rough and tough.
- Little Miss Snarker: She's a teenage girl who isn't above snarking about everything.
- Only Sane Woman: She is often the only one of the main characters who has a lick of common sense.
- Not So Above It All: But at times, she can also act goofy and immature, though not as much as Ami and Kaz are.
- The Snark Knight: When it comes to her tendency to snark, absolutely no one is spared.
- Peek-a-Bangs: Sometimes, mostly during the earlier episodes.
- Skirt over Slacks: She wears a skirt over pants.
- Suddenly Fluent in Gibberish: As said under Hidden Depths, she can talk to squirrels.
- Tomboy: She is a girl who acts masculine.
- Tomboy and Girly Girl: The Tomboy to Ami's Girly Girl.
- Tomboy with a Girly Streak: She occasionally shows feminine interests and hobbies.
- Vitriolic Best Buds: Yumi can be disrespectful and threatening to Kaz (and sometimes for a good reason), but despite that, she still likes him and views him either as a father figure and/or a close friend.
- You Gotta Have Blue Hair: Her hair is purple.
The duo's well-intentioned yet money-grubbing manager.
- Anime Accent Absence: Averted, since he has a Japanese accent.
- Butt-Monkey: He suffers a lot, especially where he has to put up with Jang Keng and Tekirai.
- Cowardly Sidekick: Kaz fits the bill on most occasions due to how often he's left Ami and Yumi in peril to save his own skin.
- The Chew Toy: His abuse is usually done as comedic effect.
- Charlie Brown Baldness: With the exception of few spots of white hair around his head.
- Eye Glasses: His glasses change shape to match his emotions.
- Fate Worse than Death: His self from the year 3000 hates living like a head in a jar because he doesn't have the means to scratch his nose.
- Greed: He'll do anything that'll make him extra money, damn the consequences.
- Jerkass: Most of the time, he ropes Ami and Yumi into cheapstake solutions with bad consequences to small problems, bad situations caused by his own greed or get-rich-quick schemes with little regard for how they feel about his decisions and the inconveniences his plans give them.
- Jerk with a Heart of Gold: Deep down, he cares about the girls and even viewed as a father figure to them, despite betraying them at times. He isn't really a bad guy if you think about it.
- Miniature Senior Citizens: He's an old man and Ami and Yumi both dwarf him.
- Money Fetish: He's obsessed with money to the point that he's always coming up with new ways he can make Ami and Yumi more profitable.
- Oblivious to Love: In "Stupid Cupids", a younger woman named Courtney fell in love with Kaz after he got a makeover. He doesn't know the first thing about love when it comes to dating her. At the end of the episode, Courtney dumped him saying he's the worst to date. Apparently, Kaz thought she was annoying.
- Paste Eater: Yumi repeatedly asks him if he ate paste. By "Cursed", he does INDEED eat paste.
- Perma-Stubble: His face is always stubbly.
- The Ugly Guy's Hot Daughters: Technically, Kaz isn't Ami and Yumi's father (just their manager), but acts like their father figure. The girls are pretty looking and cute compared to him.
Jang Keng and Tekirai
Yumi's and Ami's pet cats, respectively.
- A Day in the Limelight: In a few episodes.
- Balloon Belly: In "Kaz vs Katz".
- Bitches In Sheep's Clothing: They act like docile kittens in front of their owners, but they secretly get a kick out of tormenting Kaz to no end.
- Cats Are Mean: They terrorize Kaz for fun when their owners aren't around.
- Lady Looks Like a Dude: Jang Keng may look like a boy, but she is confirmed to be female in "Run Cat Run".
- Meaningful Name: Part of Tekirai's name ("teki") means "enemy" in Japanese, and she is indeed an enemy to Kaz.
- Pet Heir: Discussed. In "Run Cat Run", when Kaz starts acting nice to the cats, Yumi jokes that they might have inherited a fortune and Kaz found out about that.
- Sitcom Arch-Nemesis: Again to Kaz in the two episodes that focus on them.
- Spell My Name with an "S": Jang Keng's name is sometimes mispelt as "Jeng Kang".
A six-year-old psycho girl who is obsessed with Ami and Yumi.
- Abhorrent Admirer: Non-romantic variety. She is borderline obsessed with Ami and Yumi and the two rock stars are horrified by her disregard for their privacy and personal space.
- A Day in the Limelight: "Junior Tapeworm" focuses on her joining a Girl Scout troop and going to great extremes to earn every merit badge.
- Big Bad: She is the main antagonist in the game "Kaznapped".
- The Cat Came Back: In her debut, she keeps returning in spite of everything Ami and Yumi try to get rid of her.
- Catchphrase: Every episode she's in has her say "I'm your number one fan!" or some variation thereof at least once.
- Genki Girl: She is always cheerful and exciteable.
- Girly Bruiser: In "Junior Tapeworm".
- Loony Fan: Definitely, given how obsessive she is in pursuing Ami and Yumi and how little regard she gives their personal space.
- You All Look Familiar: Many clones of her appear as minor enemies in the online game Puffy Treasure Island.
Kaz's adopted puppy who eats cat food.
- Big Eater: Has an enormous appetite, especially when it comes to cat food.
- Dogs Are Dumb: Demonstrated by how he just sits there panting and doesn't do any of the tricks Kaz asks him to.
- Eye Glasses: Just like his owner, Kaz, his glasses change shape to match his emotions.
- Precious Puppy: Kaz seems to adore him very much.
- Uncatty Resemblance: Bears a strong resemblance to his owner, that this has resulted others mistaking him for Kaz.
The Talent Suckers
A vampire rock trio from Slovakia that "sucks" people's talents.
- A Day in the Limelight: "Talent Suckers Return" and "A Grave Mistake".
- Dark Is Not Evil: They may look threatening, but they're not really malicious.
- Daywalking Vampire: Sunlight does not seem to affect them.
- Epic Fail: In "Talent Suckers Return", they give such a lousy show, the guy who hired them insists they should pay him instead of the other way around.
- Freudian Trio: Nicolai is the Id; Mitch is the Ego and Vlad is the superego.
- Friendly Enemy: With Ami and Yumi, in later episodes.
- Friendly Neighborhood Vampire: They're vampires who, at least after their debut episode, are good-natured.
- No Celebrities Were Harmed: Vlad and Nicolai's voices were based off of Bela Lugosi and Peter Lorre, respectively.
- Our Vampires Are Different: Instead of sucking blood from people, they "suck" talent.
- The Quiet One: Mitch doesn't talk as much as Vlad and Nicolai do.
- Work Off the Debt: Their plot in "Talent Suckers Return" is that they have to work off the money the owner of the stadium lost by having them play there.
A 16-year-old girl who was a former band member and was also Yumi's friend.
- Anime Accent Absence: Just like Ami and Yumi, she lacks a Japanese accent.
- Bitch in Sheep's Clothing: Definitely. She was nice to Yumi while purposely torturing Ami. All this happened until she plotted her revenge to get rid of both of them and became the star of the band.
- Companion Cube: She treats her keytar as a sentient being.
- Curtains Match the Window: Her eyes are green like her hair.
- Evil All Along: It turns out in the end that she holds a grudge against her former bandmates and wants them dead.
- Hidden Depths: Shown to drive the tour bus and can even lift the girls and all of their instruments with only one finger.
- Idol Singer: She used to be part of the band until Ami kicked her out.
- I Just Want to Be Special: The truth is that she just wanted to be loved like Ami and Yumi and get the same attention as them. It isn't never explained how the audience did not notice her that much.
- Manipulative Bitch: She was nice to Yumi to keep her from realizing how horribly she was acting toward Ami.
- Remember the New Guy?: She's established as a former member of Puffy AmiYumi even though no prior episode featured her or acknowledged her existence.
- Running Gag: Mistakenly calling Ami her wrong name, Arthur.
- The Strategist/Teen Genius: She comes up with a complex plan to get back at her former bandmates.
- Tomboyish Ponytail: She's a tomboy with a ponytail.
- Tomboyish Voice: She has one when she's being insane.
- Town Girls: The neither to Yumi's butch and Ami's femme.
- Troubled, but Cute: She's as sweet-looking as Ami and Yumi, but has issues.
- Villainous Breakdown: She goes into a meltdown when the audience boos her for trying to humiliate Ami and Yumi.
- We Will Meet Again: Her single episode ends with her vowing to get even with Ami and Yumi.
- Who's Laughing Now?: "Look at them, keyboard guitar! So much for Puffy Arthur Yumi!"
- You Gotta Have Blue Hair: Her hair is green.
Ami and Yumi's former crush in "In The Cards".
- Broken Pedestal: To Ami and Yumi, but mostly the former. They competed against each other in the Stu-Pi-Doh! card game in order to win his affections. Ami won, but it turned out Chad only cared more about the game more than relationships when he challenged her himself, much to her heartbreak. And then he beat her in just one move.
- Jerk with a Heart of Jerk: He dumped Ami (despite winning a duel between her and Yumi) at the end of "In The Cards" just so he can beat her in a game called Stu-Pi-Doh!.
- Nerds Are Sexy: He's a geek obsessed with the Stu-Pi-Doh! card game and Ami becomes smitten with him (Yumi as well once she admires how prideful he is in being Stu-Pi-Doh! champion).
- Your Cheating Heart: Cheated on Janice to date Ami and Yumi when they were a lot like her in one episode.
- Youthful Freckles: He has freckles to show he's an adolescent.
Ami and Yumi's childhood friend from Camp Youwannasushi, who wants to be a superhero like his favorite comic book hero, Mangbee Man.
- Adorkable: Comes off as awkwardly endearing because of his belief that he has super powers.
- Cloudcuckoolander: Considering his belief that he's a superhero and tendency to act like he has super powers, it goes without saying that he's rather odd."Here's my card...oh wait. Stand back! I'll give you the card in lightning speed! NGINGINGINGING!"
- Implied Love Interest: Has one on Yumi.
- Kid Hero: He's around Ami and Yumi's age, which is 16.
- Nice Guy: Quirky nature aside, he does stand for doing the right thing and is cordial to Ami and Yumi all the time.
- Nice Hat: He wears a cool helmet.
- Origins Episode: The episode "Secret Origin" reveals the origin of his superhero obsession.
- Plucky Comic Relief: He's an associate of Ami and Yumi's who tends to provide comic relief whenever he's around.
- Third-Person Person: Most of the time, he refers to himself as "Atchan".
Ami and Yumi's former bodyguard and friend.
- The Big Guy: He's large and willing to do physical work, mainly defending Ami and Yumi from perceived threats.
- Catchphrase: He frequently ends his statements with "Unquote."
- Dumb Blonde: He has blond hair and isn't very bright.
- The Klutz: He's very clumsy.
- Hulk Speak: He refers to himself in third person and doesn't use complete sentences.
- Lawful Stupid: He's so dedicated to protecting Ami and Yumi that he'll attack anyone who gets near them unprovoked.
- Strong Family Resemblance: "Hired Help" introduces his mother, whose face looks like his.
A girl King Chad dates in "Janice Jealous".
- Emotionless Girl: She isn't very expressive.
A sinister land developer who usually tries to tear down beloved places for his own selfish needs.
- Arc Villain: Of Save the Farm and Arbor Day.
- Gonk: His face is rather ugly.
- It's All About Me: Only cares about tearing down places so he can make more money and doesn't give a damn about who gets hurt in the process.
- Rich Bastard: He's wealthy and likes to cause trouble.
- The Reveal: In Kaznapped, he is a disguise made by Harmony.
Personal. Automated. Lookout.
- A.I. Is a Crapshoot: His flawed programming on how to neutralize people other than Yumi caused him to try and indiscriminately neutralize everyone.
- Antagonistic Offspring: He referred to Yumi as "The Creator".
- Back from the Dead: In The Genie and the Amp, for reasons unknown.
- FaceHeel Turn: Once he realized he shot Yumi, he became corrupt.
- Kill All Humans: His purpose after his flaw was noticed is to kill everyone.
- Killed Off for Real: In "The Genie and the Amp".
- Love Makes You Evil: His protection for Yumi eventually makes him corrupt once he shot Yumi.
- Split Personality: He has one between his natural and corrupted state.
- Would Hit a Girl: He tried to shoot at Yumi multiple times.
- The Noseless: Becuase he's a fish.
- Spirit Advisor: He was used by the girls to answer their questions.
Ami's favorite manga hero, who is a majestic knight.
- Green Eyes: Or green eyes with no pupils.
- Knight in Shining Armor: A literal example, since he's a hero who happens to be wearing medieval armor.
- The Rival: To Decibel Destroyer, before they team up.
Yumi's favorite manga hero, who is a robotic amplifier.
- The Rival: To Knoble Knight, before they team up.
The villain who is against both Knoble Knight and Decibel Destroyer. He also longs for his PHD.