This achievements has to be done in one playthrough. You can die inbetween these kills. The enemy MUST be in Manic mode when it dies for this to count as a close range kill. An easy way is to get to the point where there are 3 slow moving round blue enemies. Press all 3 to turn them green and they will move slower. Now put the tip of your nose into the enemy and back up as needed until it dies. The little orange shape in the middle of your ship is what can't touch anything, but the rest of the ship can. After they die, you can choose to get yourself killed if you have time (on last remaining enemy). There are two spots where you can do this, very early on at the start.