Letz Kobayashi, born Letz Cofan, was one of three orphaned children from Side 7 who found refuge aboard the Earth Federation assault carrier White Base during the One Year War. He formed a close-knit group with fellow orphans Katz Hawin and Kikka Kitamoto, serving as both mascots and occasional troublemakers for the crew. During White Base's missions, Letz and the others witnessed or participated in critical events, including Ramba Ral's final assault and Char Aznable's infiltration of Jaburo headquarters. At Jaburo, they helped locate and dispose of bombs planted by Char, influencing the decision to keep them aboard despite earlier plans to disembark. Later, during the Battle of A Baoa Qu, the children manifested nascent Newtype abilities, collectively reaching out telepathically to guide Amuro Ray to the lifeboat carrying White Base's survivors after the ship's destruction. Following the war, Hayato Kobayashi and Fraw Bow adopted Letz alongside Katz and Kikka. The family visited Amuro Ray's home in Cheyenne, Wyoming, before settling in Japan. Letz maintained a close relationship with his adoptive mother, assisting with her newborn child. Unlike Kikka, who later pursued journalism studies in space, Letz remained on Earth with the Kobayashi family at their Shizuoka home. Approximately a year after Amuro Ray's presumed death in the Second Neo Zeon War, Letz greeted Kikka during her Christmas break visit to Shizuoka. Both expressed surprise when Fraw Bow declined to participate in a Federation memorial service honoring Amuro and other war casualties. An indirect appearance occurs during Mobile Suit Gundam Unicorn, where background characters resembling adult versions of Letz and Kikka watch Mineva Zabi's public revelation about Laplace's Box, hinting at their continued presence in the Universal Century timeline.