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 was Yoshi's best friend and childhood friend. He and Yoshi consider themselves as brothers sometimes and they were both raised by the Ancient One. Mashimi was a guardian of the utroms before he became a Foot ninja when he joined the Foot Clan.


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 but Yoshi refused and returned it to the Ancient One.

The Ancient One was surprised of Yoshi's honesty that he offered Yoshi and Mashi that they can keep the coin if they can snatch it from his hand. Mashimi failed to snatch the coin but Yoshi succeeded. The Ancient One offered him to buy food but Yoshi requests that Mashimi can join too. The Ancient One reluctantly agrees and takes them to his home and gives them food. He raised them and taught them ninjustu.

Yoshi and Mashimi fell in love with the same girl named Tang Shen who also was raised by the Ancient One.