An executive of the large corporation Tanto Tempo, based in the Avalanche colonies on the Moon. Rosario is one of the six executives on Tanto Tempo's Board of Directors, and he is in charge of the Banking Department (Western Bank). Although he was once a Mobile Suit pilot for a crew of space pirates, he was discovered by Ted Morugaton and ended up in his employ. After that, Rosario quickly distinguished himself and soon became Ted's right-hand man. However, that was not enough to satisfy him, and he secretly longed to take Ted's place entirely. Rosario's skills as a pilot are as sharp as ever, and he pilots the Gundam Vual in combat.