Hi-Fi RUSH

Find this at the arcade machine in your hideout (after you beat the game).

There are 25 floors, and you can cheese this (and the whole game) pretty easily by focusing on partner upgrades and parry health. Then just spam partner activation, partner cycle, and parry on every beat. When the enemies are stunned, attack. This is pretty brain dead, but effective.

There are also challenge stages (purple light) that will give you increased power ups. Later in the run I completed one and had a choice between x5 damage or “x3 damage and x3 defense,” for a total of SIX upgrade points instead of the usual one. If you don’t care about your score, you should always give those a try.

If you get the “bug”(negative effect) that increases the damage you take when your combo is higher, be sure to sit and parry every so often and let your combo disappear, otherwise you can easily get one hit killed.

Also, you can die as much as you want, and simply continue. I did and still got the achievement. You can probably also save your run and quit, but I did it all in one go.