Who is Gaston from Deep River and what is their importance?

Gaston is a volunteer who works at the hospital where Tsukada dies. Gaston is a foreigner, and he believes in God. When Tsukada asks Gaston if his God would forgive Tsukada for eating the flesh of a dead soldier to save himself and his friend, Gaston tells him the story of climbers trapped in the Andes. The dying begged the living to eat their flesh after their deaths, so that they might survive. Tsukada seems to get some comfort from this story. After Tsukada's death, Gaston disappears from the hospital.