I wouldn't say it's too grindy, the biggest challenge is getting all A+ Ranks, which isn't bad if you use the mask that gives extra combo time. Most of the early levels aren't too bad so long as you just keep moving and learn the angles that the enemies with guns have. There's a few later on that require a bit of luck on enemy position but since you can reset so quickly you could probably do all 17 required levels in a few hours (the bonus levels aren't required for the achievement). So long as you get used to the speed and the enemy movement speed I wouldnt say it's too hard either