Daiba is the audience surrogate, the viewer's gateway to Harlock's world. The 14-year-old son of a scientist who was killed by the Mazone, he joined the Arcadia crew following the death of his father. He lost his mother in a disaster on the Neptunian moon Triton when her pleas for help were ignored by the indifferent government. Tadashi is sometimes in conflict with Harlock early in the series, but he would become a trusted part of Harlock's senior staff as the series progressed.

(Source: Wikipedia)