Gaijin Charenji 1 : Kiss or Kill

The kill gun is better than kiss gun because its range goes farer, so if you are following all the achievements, try to get first good karma to finish the game and then starts a new game again and get the maximum negative/bad karma as soon as you can. To do that just select the skull gun and kill as many enemies as you can. Try to let the enemies accumulate, avoiding then for some time and then shoot to get bonus points. There are some levels with a lot of enemies spawning even after the end of the level is available, like in the space invaders type levels. But how the kill gun can kill almost everything, even the circular blades, there are plenty of opportunity to increase karma. After finishing the last boss in campaing, you should focus in survival mode achievements since you save the karma status from the campaing, It should be easy.