The simplest way of completing the Hell Survival (100 waves) is to use Manpukumaru at max level and any Extar, I used Koharu for +50% defence.
1. Manpukumaru HEALS by special attack (you have to hold the button to start eating, then mash it really fast to finish eating earlier). Just don't forget to button mash or she'll eat for VERY long time.
2. Her ultimate Drive attack is insane. It one-shots bosses, including the full power ones. Basically all you need is to get her to Final Drive, then accumulate enough energy for bosses each 10 waves. One ultimate attack is enough to bring any boss to knees. It's so powerful that the usual Valkyries at each 10 waves, if you are unlucky, will be thrown away from the airstrike zone by the amount of force applied.