|“||How dare you ask why! You betrayed ME! We were like brothers, but you took everything and left me with nothing! NOTHING! Now I take everything from you, including your life.||„|
|~ Yukio Mashimi to Mortu and Hamato about his betrayal.|
Yukio Mashimi is an antagonist in the 2003 incarnation of Teenage Mutant Ninja Turtles, serving as the main antagonist of "Tale of Hamato Yoshi". He was once Yoshi's childhood friend and adoptive brother until he betrayed him.
He was voiced by Sean Schemmel.
In Japan during the 1960s, Yoshi and Mashimi were orphans on the street begging for food and money. One day, they found a five yen coin that fell from a short old man named the Ancient One. Mashimi told Yoshi that they should keep it to themselves, but Yoshi refused and returned it to the Ancient One. The Ancient One was surprised of Yoshi's honesty that he offered Yoshi and Mashimi that they can keep the coin if they could snatch it from his hand. Mashimi tried and failed to snatch the coin, but Yoshi succeeded. The Ancient One offered him to buy him food, but Yoshi requested that Mashimi can join too. Though he sensed darkness in Mashimi's heart, he Ancient One reluctantly agrees and takes them both into his home. He then chose to raise them as his own sons and taught them the way of ninjitsu. As they grew, they became best friends who did everything together.
At some point, the Ancient One then took in another orphan: a beautiful and compassionate young girl named Tang Shen. Yoshi and Mashimi both fell in love with her, but Tang Shen herself was in love with only Yoshi, which made Mashimi jealous. One day, a little rat made its way into the Ancient One's home. Mashimi attempted to kill the rodent with his sword, but Tang Shen stopped him and took the rat in as a pet. Then one night, while the three of them were out exploring Tokyo, they came across Mortu, in his human disguise, under attack by soldiers of the Foot Clan. Yoshi and Mashimi put their martial art skills to the test by fighting off the ninja. They were victorious, but another Foot soldier lying in wait attempted to kill Mashimi while his back was turned. Mortu saved him by pushing him out of harm's way, but got his arm cut off in the process, which revealed him to be an Utrom to Yoshi and Mashimi. Impressed by their skills in battle, Mortu offered them the chance to become Guardians of the Utroms and learn everything about what they have witnessed. Even though the Ancient One strongly forbade them from doing so, they accepted Mortu's offer.
During their time as Guardians, Yoshi rose through the ranks until he reached the highest rank, while Mashimi failed to be promoted, making him even more jealous then before. One night, while secretly seeing Yoshi and Tang Shen kissing, Mashimi's jealousy of Yoshi finally caused him to snap, turning any brotherly love he had for Yoshi into hatred. When Yoshi left the scene, Mashimi surprised Tang Shen when it started to rain. Tang Shen was relieved that it was just him at first, but then became scared as he angrily stared at her. After hearing her scream, the Ancient One rushed outside to find Tang Shen's lifeless body on the ground and Mashimi missing.
After murdering Tang Shen, Mashimi then went to the Foot Clan. He told them everything he knew about the Guardian's base, and as a reward, their leader, the Shredder, made him a high-ranking member of the Foot Clan. Together, they attacked the base, surprising both Yoshi and Mortu with his presence by wearing a Foot Clan uniform. Mortu was angry that the young man whose life he saved before joined the very enemy that nearly killed him, while the shocked Yoshi asked why Mashimi would do this. Enraged by this question, Mashimi claimed that Yoshi betrayed him by taking "everything" and leaving him with "nothing", and that he will now take everything from Yoshi, including his life. However, Mortu initiated an evacuation protocol that Mashimi didn't know of, allowing the Utroms and Guardians to escape. Mashimi attempted to chase and kill Yoshi, but was blocked by the door to the pod they escaped in. The Shredder was livid that his enemies had survived and blamed Mashimi for it, though Mashimi assured that he wasn't aware of the escape pods.
When Yoshi returned home to tell the Ancient One of Mashimi's betrayal, he himself learned of Tang Shen's death at the hands of Mashimi. Consumed in hatred for his former friend, Yoshi stormed the Foot Clan's hideout to kill Mashimi for his betrayal. After defeating several Foot soldiers and reaching the Shredder's throne room, he called to Yukio Mashimi, who the Shredder summoned to his side. Yoshi challenged Mashimi to a duel to the death, but Mashimi laughed this off, stating that he has no need to fight Yoshi alone with the rest of the Foot Clan at his side. However, the Shredder then stated that Mashimi will fight Yoshi by himself, and only if he succeeded in defeating Yoshi will the Shredder forgive Mashimi for allowing his enemies to escape and spare his life. Reluctantly, Mashimi obeyed his new master.
Facing Yoshi alone, both he and Mashimi take defensive stances. Mashimi then states how their story will end the same way as it began: with just the two of them. Yoshi rebukes this by stating that their story will end with one of them alive, and then proceeds to punch him away. Mashimi then draws his sword and jumps towards Yoshi, focusing all rage into a single strike, but Yoshi does the same. As they land, the only damage Yoshi sustained was a tear in his uniform, while Mashimi was dealt a fatal blow. Before collapsing in death, Mashimi begged Yoshi to forgive him.
After Mashimi's death, Yoshi then escapes Shredder's fortress and travels to New York city to continue aiding the Guardians, taking along Tang Shen's pet rat, who he names Splinter to remind himself of Tang Shen's love and Mashimi's betrayal.