Captain Harlock and the Queen of a Thousand Years

The Mazone, a race of sentient plants, hatch a plot to seize Earth after their own planet is destroyed. A lone scientist attempts to warn the people of Earth, but at the cost of his reputation and life. The titular Harlock is blamed for the various instances of the Mazones' attacks upon the Earth, and, despite being an outcast amongst his own people, plans to stop the Mazone and save humanity from the alien threat with aid from Princess Olivia, next in line to throne of Millennia, the Mazones' supposed allies in the invasion.

(Source: Wikipedia)