Marco to Ginga Ryuu

Marco, an orphan with missing memories, and Arco, a dragon who rules the galaxy, were hunting for treasure in space! On one of their adventures, Marco was given a clue to the whereabouts of her mother. Their next stop, her birthplace - Earth!

(Source: Steam)

Note: (OVA bundled as a bonus Blu-Ray disc with the physical release of the game)