Julie Yamamoto

Julie Yamamoto is Ben's primary love interest, and later becomes his girlfriend. She first appeared in Ben 10 Returns: Part 1 at Ben's soccer game and congratulates him. On their first date in Pier Pressure, she discovers Ben's powers, but much to his surprise, she finds it "cool." She usually wears a black t-shirt mostly hidden under a pink sweatshirt, and a white mini skirt. When playing tennis she is shown wearing white wrist bands, shirt, and skirt. In Fame, when Ben's secret was exposed, she kissed him on the cheek for some encouragement. In Hero Time, she was kidnapped, until Ben saved her life and called her "his girl" and she smiles.

Appearance
Julie wears a black t-shirt mostly hidden under a pink sweatshirt and a white mini skirt. When playing tennis, she wears white wrist bands, t-shirt and her own skirt. She has short black hair with bangs, and white shoes.

Ben 10: Alien Force
Julie first appears in Ben 10 Returns: Part 1, where she congratulates Ben after his team won a soccer game.

In Pier Pressure, Ben asked Julie out on a date. It was interrupted by an alien (whom they named Ship at the end of the episode), who kidnapped Julie. During the rescue attempt, Julie found out about the Omnitrix, which she finds cool. In the end, it was revealed that Ship was trying to lead Ben to his "father", Baz-el, whose ship crashed and was about to explode. Ben and Julie helped fix Baz-El's ship and he left Ship with them, saying that he and Ben have a bond. On the walk home, Ship takes off after a passing truck, and Ben and Julie walk home, holding hands.

In Save the Last Dance, when Big Chill takes control of Ben's personality and starts eating every metal object in sight, Julie follows him on her motor scooter and alerts Gwen and Kevin and she tells them where Ben is headed. Gwen and Kevin manage to subdue Big Chill, only to discover that Big Chill was building a nest for eggs he had laid. The eggs hatch into baby Necrofriggians, and Kevin teases Ben about being a "mommy". As Julie takes Ben home on her motor scooter, she unsarcastically tells Ben that she thought he made a great "Mom". Ben also stated she gets straight As.

In Pet Project it was revealed that Julie is keeping Ship as a pet. She helped save Ship from the Forever Knights.

In War of the Worlds, Julie helped Ben fight against the Highbreed invasion and it turned out that she apparently had a curfew. She also seems to show a deal of concern and care for Ben. At the end of War of the Worlds Part 2, Ben and Julie get close to kissing, but decided against it, as Gwen, Kevin and Max were all looking. Ben then tells her that he will walk her to school the next day and Julie gets home by riding in Ship after giving Ben a loving smile.

In Vreedle, Vreedle, the Vreedle Brothers, hired by Baz-El to return Ship to him. As Julie refused, the Vreedle Brothers started being more aggressive, and Ben and Kevin go in court to claim their right on Ship against Baz-El, while Gwen stayed on Earth to keep Julie and Ship safe. When the Vreedle Brothers came back, Ship revealed he can "merge" with Julie, giving her a powerful robotic suit she can use to fight. Ben is eventually able to get the judge's favor, and Baz-El reluctantly accepts Ship is now Julie's.

In Single-Handed, Julie finds Ben's detached hand and takes it to Gwen and Kevin. She later uses Diamondhead's hand to fight Sunder. During the fight Gwen helped her keep Ben's hand away from Sunder but Julie wound up being used in a trade when Sunder caught her. After Sunder was knocked out, she, under Kevin's instructions, held a beam on Ben's arm while they used Sunder's axe to put Ben back in one piece.

In the The Final Battle: Part 1, Julie is briefly seen playing with Ship.

Ben 10: Ultimate Alien
In Ben 10: Ultimate Alien, Julie is now sixteen-years old and is helping Ben's team from time to time.

In Fame, Julie comforted Ben when his identity was revealed to the world. When he thought everybody would hate him, she kissed him on the cheek and told him that not everybody hated him.

In later episodes, Julie became more skeptical of Ben when the fame slowly goes to his head, which causes friction in their relationship.

In the second episode, Duped, Julie became very upset with Ben for not spending time with her, as he chooses to watch the movie version of "Sumo Slammers" as his real self while leaving an immature Ben with her.

In Hero Time, she became jealous of Jennifer Nocturne after she kissed him when he saved her life. Later, she was kidnapped by Captain Nemesis. When he tried to kill her and Jennifer, Goop saved Julie. Goop then called her "his girl", she smiles and she forgave Ben for his flaws. She then assisted in taking down Overlord.

In Absolute Power: Part 2, she use Ship's to help Gwen escape Kevin. She later appeared in her battle suit.

As shown in Eye of the Beholder preview, Julie and Ben were going through relationship troubles. Ben apologized to Julie for being such a jerk and he promised to try to be a better boyfriend, which makes them both happy.

In Revenge of the Swarm, when Ben and Julie arranged a date, she was kidnapped by the Nanochips at the behest of Elena, who was jealous of her. When Armodrillo freed Julie before Elena used the swarm in an attempt to suffocate Armodrillo, Julie was able to convince Elena to stop her Nanochip activity if she really loves Ben, as well as Julie herself loves him. Then she watches Elena kill herself to stop the Nanochips and Ben's life is saved. As Ben mourned Elena's supposed death, Julie gave him some comfort before they both drove home in Ben's car.

In Greetings From Techadon Julie and Ben competed in a golf course and Ben won, thanks to Brainstorm but Julie was shown not to be happy and accused Ben of cheating in the death hole. At the end of the episode, Ben said he must go and have a rematch as promised to Julie.

In The Flame Keeper's Circle, she joins a philanthropic organisation called the Flame Keeper's Circle, as she accepts their theology of using Diagon's Technology to advance Earth's humanitarian efforts and create a utopia. She tries to get Ben and Kevin to understand but fail, becoming quite angry at Ben for this as he laughed in the Cult Leader's face and himself uses alien technology to protect Earth. She believed this to the point of pretending to be a hostage for Conduit Edwards to make Ben revert from Big Chill. She again tries to preach the benefits of the Flame Keeper's Circle to Ben but realises her mistake when Ben tells her that it is Vilgax. She later maintains a belief that alien technology should not be kept from humans although is far less fanatical.

Powers and Abilities
Being an ordinary human, Julie doesn't possess any super powers herself, although she's quite good at tennis, and shows some fighting ability in Pet Project. She's also the only one who can fully command Ship, making her a competent ally.

In Vreedle, Vreedle, Ship reveals that he can "merge" with Julie. When Ship enveloped her, he became a battle suit. In this suit, she demonstrates enhanced strength and great damage resistance, as well as the ability to fire various powerful weapons.

In The Eye of the Beholder, it turns out that Julie can understand what Ship's language.

Ben 10: Alien Force

 * Ben 10 Returns: Part 1 (first appearance)
 * Pier Pressure
 * Good Copy Bad Copy
 * Save the Last Dance
 * Pet Project
 * War of the Worlds: Part 1
 * War of the Worlds: Part 2
 * Don't Fear The Repo
 * Single-Handed
 * The Final Battle: Part 1

Ben 10: Ultimate Alien

 * Fame (first re-appearance)
 * Duped
 * Hero Time
 * Absolute Power: Part 2
 * Eye of the Beholder
 * Revenge of the Swarm
 * Greetings From Techadon
 * The Flame Keeper's Circle
 * The Perfect Girlfriend

Trivia

 * Ben seems to not call Julie very often as hinted by Gwen.
 * Julie is a Japanese descent, as her last name is "Yamamoto", which is a common surname in Japan.
 * This is confirmed by Eugene.
 * Ironically, her voice actress, Vyvan Pham, is a Vietnamese descent.
 * Julie owns a motorized scooter.
 * Julie resembles a character that was on Friends, also called Julie, an Asian-American girl, with almost the same personality.
 * Julie's battle suit has a strong resemblance to the Samus Aran's Chozo Powersuit even to the point of having similar weapons.
 * Ben and Julie shared their first on-screen kiss (on the cheek) in the Fame. However, it should be noted that this is confirmed to be canon.
 * Like Ben, Julie has not had a change of clothes in the Ultimate Alien series until "The Perfect Girlfriend".
 * Gwen considers that Julie is the "only one who has common sense among the four of them" (note how by "four", Gwen includes herself), as she always avoids trouble.
 * Julie in many episodes, acts as Ben's "voice of reason". It's also shown that no one can comfort Ben better than Julie.
 * Like Ben, Julie also likes chilli fries, smoothies and Sumo Slammers.
 * Yamamoto in Japanese means 'one who lives in the mountains’ or ‘at the foot of the mountain’, this is one of the ten most common surnames; it is found predominantly in central and west-central Japan.
 * It is confirmed that Julie's family is from Denver. See here.
 * Unlike other characters, Julie has no highlights in her eyes, except in Ben 10 Returns Part 1.
 * Julie can understand Ship's language.
 * When Julie appeared in Revenge of the Swarm, she seemed to have no jealous feelings of Elena trying to keep her away from Ben until she convinced Elena to save his life, but in Hero Time, you can see her being jealous towards Jennifer Nocturne, that she still cares for Ben. It's possible she had learned of Elena just recently in Revenge of the Swarm until Ben saved her life.
 * Every episode that Julie shows up, Ben uses Humungousaur or Jetray or both.
 * Ben and Julie's first kiss was in Fame, but in a comic book, they shared their first kiss on the lips.
 * Julie does resemble the main character in the short-lived sitcom, "Phenom" which also involved a young teenage tennis pro, and coincidently also starred Ashley Johnson (aka the voice of Gwen Tennyson).