It's an event that happens every start of the month, yes. Every single time you sortie, you have a chance of finding a lost Abyssal transport ship and her escort instead of the usual randomly-generated enemy fleet at a non-boss node. And when you attack her, you can loot her for war spoils if you successfully sink her and her fleet.
Said war spoils are clearly her panties.
That's because you never go outside at all!...and that's how bad the current situation is.How dare they! We should go massacre those humans!So you called me all the way over for a meeting just for this?Counterattacking is a given, but...Eh, this 'pantsu' thingy or whatever, it's not like it matters if we wear them or not anyway.They snatched away all our panties!We cannot sortie without any underwear. After all, that's the only thing we wear in our standing CG art.You're all going commando right now, are you not?