This song is not in the game (what's there is actually inferior) but makes total sense after everything is over in EDF 5. While the battle song is subpar, EDF 5 improves on practically everything from 4.1.
Taking place in what I assume is an alternative timeline, we actually fight aliens this time. These aliens, the frogs (I DEMAND ALIENS RIGHTS) and actual grey aliens, replace the classic EDF enemy: Hectors. While it saddens me that there are no Hectors but the aliens brings A LOT to the table. The frogs are the nearly 1:1 replacements to the Hectors with a twist: you can shoot off limbs for a much needed, if gory, layer of tactical crowd control. Of course they can regrow limbs but you can just one-hit kill them with a strong enough shot to the head. Easy enough. The grey aliens though, they wear armor. At minimum they take two well placed shots to kill. If not, prepare to stunlock them with excessive firepower. Oh yeah, these aliens know to flank you too... These two aliens poses a threat that the Hectors never were.
On the player's end, there is too many to even mention them all. My top three would be 1) the improved loot system where weapon crates means something (for weapon upgrades) and what is picked up can apply for all classes; 2) while still very powerful, the wing diver received a much needed check on how her weapons work so she's not completely OP; and 3) no more double stacking on weapons during loadout which in MP really changes things. Like there's many more improvements like how the fencer isn't stuck a with needing an dash cancel loadout now but yeah... I love a lot of the changes done with EDF 5.
A lot of craziness abound. Last mission spoiler:
I LOVE THIS SERIES SO MUCH