Robert Marita is a wheelchair-bound university professor living in Japan. His past includes service as a U.S. Army lieutenant in the Vietnam War roughly two decades before the main events. During a Ranger-type mission, Viet Cong forces ambushed his team in the Vietnamese jungle. Robert became the sole survivor, suffering severe injuries during his escape.

Deep in the jungle, he discovered an abandoned temple inhabited by Lamina, an unearthly girl with green hair. She healed Robert's wounds using a mysterious green powder, which also regenerated the surrounding jungle. A bond formed between them during this time; Robert named Lamina and voiced his disillusionment with the war. When Viet Cong forces located the temple, Robert intentionally led them away to shield Lamina, resulting in further injuries that left him permanently crippled.

Hospitalized after the war, Robert met and married a Japanese nurse. They moved to Japan, where their son, Subaru Marita, was born. Robert's wife died while Subaru was still young. Robert became a university professor in an unspecified field, described as penniless. He retained profound memories of Lamina and shared his experiences with Subaru.

Years later, when Subaru joined a research expedition to Vietnam, Robert entrusted him with his harmonica—the same instrument he played during his time with Lamina—hoping Subaru might find her and return it. This harmonica later proved instrumental in awakening Lamina from stasis when Subaru played it at the temple. Robert's character arc centers on his wartime trauma, protective instincts toward Lamina, and enduring influence on his son's journey.