Yumi Yoshimura is the main protagonist from the TV show, Hi Hi Puffy AmiYumi and is the fictionalized version of the real life Japanese pop star of the same name. She is a goth, similar to Sam Manson from Danny Phantom. She is Ami Onuki's best friend. Yumi and Ami are real-life Japanese rockstars.
She dresses in a rock style with studded necklaces and bracelets, a light purple T-shirt with a skull on it, a black miniskirt, and black knee high boots.
For night time, Yumi wears a black or a white sleeved nightgown with a skull in the middle. For swimwear, Yumi first wears green bikini in the episode "Robo-Pop," but in "Surf's Up" and til the rest of the series Yumi now wears a purple string bikini with half a skull on the bikini top and the other half on the bikini bottom.
For formal wear in "Movie Madness", Yumi wears a black glittery glamorous dress with the same studded choker from her main outfit and wears black opera gloves.
For ninja wear, Yumi wears a black sleeveless ninja outfit and wears a black balaclava. As a magician assistant, she wore a pink hairband, a gold necklace, a pink tube top, a pink miniskirt and gold pumps.
In "Secret Origin" and the flashback of "Super Zero", she wore a black long sleeve shirt, a white flounced skirt, white socks and black Mary Janes shoes.
In the pilot, she had her hair being more purplish-toned and lighter, a dark magenta shirt with the skull having a green outline, slightly darker skin, freckles, a gray-cyan glove (on her right hand), spiked bracelet (on her left hand) and spiked collar, light bluish-purple socks and boots with shades of purple. She also had square-framed sunglasses on her hair in some shots.
Being the youngest, Yumi is also more impetuous than Ami and rushes headlong into a decision before thinking. However, Yumi has a mature side, too, and sometimes reasons with Ami's childish obsessions.
Possibly is a good loser because in the episode "In the cards" Ami defeats her in a Stu-pi-doh game (A parody of Yu-Gi-Oh) and not have hard feelings.
Yumi loves things like ninjas, monster trucks, car crushers and anything else rough and tough. She is a tomboy. When she was younger in the episode Opera Yumi it is shown that she was a opera singer since birth, but rebelled to go to rock. She also commonly disrespects Kaz. Yumi was also hypnotized by her old opera teacher and had to recused by Kaz and Ami.
Yumi can drive the tour bus, talk to squirrels, eat a lot of food if she is very bored and make a huge mess like Kaz and Ami. Yumi is also a ninja due to her training in Ninjacompoop.
- The skull on Yumi's T-shirt has the same facial expressions as she does and seems to have a mind of its own.
- Yumi is similar to Samantha Manson from Danny Phantom because of their gothic appearance and are voiced by the same English-language voice actress, Grey Delisle.
- Yumi is also similar to Gwen from the Total Drama series.
- Yumi's voice is almost like Mandy from The Grim Adventures of Billy and Mandy because both she and Mady are voiced by Grey DeLisle.
- Despite acting like the oldest, the real Yumi Yosimuro is the youngest of the two.
- In "Ski Sick" It is shown that Yumi is bad at skiing.