Age 8 (MSG), 16 (MSG-Z) During the One Year War, Katz was one of the orphan kids that lived in the White Base. In Mobile Suit Zeta Gundam,

Spoiler

Katz is the newly adopted son of Hayato and Fraw Kobayashi. He becomes an AEUG soldier and follows under Char's orders. He's not truly experienced with War and tends to become punished for many of his actions.