Star Arthur Densetsu I: Wakusei Mephius

In the year 3826, the Galactic Federation is at war with Jamil, an enemy from outer space, and unarmed planets are being destroyed one after another by Jamil's vicious fleet. Meanwhile, Star Arthur Mirvac descends on the planet Mephius in search of the legendary sword Raysword to crush Jamil's ambitions...
This game is known for being a very early adventure game, and for releasing on three cassette tapes. It uses a both kana command input and cursor selection.