This shouldn't be hard at all considering this level acts as a basic tutorial for the game.
After you defeat the boss and the loading screen comes up, you'll get the achievement.
Here's a video of the first level, I take no ownership of this clip, it belongs to it's owner.
If you're new to Space Channel 5, this is a rythm based game that's highly dependant on pressing the correct direction your opponent shouts as well as on the same beat as them.
It'll take a bit of doing to get used to, but it's not the hardest thing in the world.
If you're further having trouble, go into the control options and set every action to "A" that way you just have to press the A button on beat and not have to worry about a direction.