Great find indeed...
I searched further, and found out that it is an episode from the anime Pygmalio, broadcasted in a few European countries.
There isn't much about that on the web. I've only come across
a short thread in a Jap blog.
Google Translator will help anyone interested into the texts.
The whole story comes straight from No.22 of a (quite gory, actually!) manga which I've been able to dig out
here.
The provided link sends directly to the beginning of the big battle: page 60 corresponding to page 115 of the comic. There isn't much to see before that.
What I also managed to locate is a HD version of the episode,
here and
here.
It is dubbed in French, which I understand better than Spanish, then I managed to follow the plot of the episode.
Briefly... Caral (the little boy) is a demi-god whose princess friend has been poisoned. An antidote is available in the central tower of a labyrinthic fortress, comprised of a series of fortifications guarded by a huge army of female warriors: tens of thousands (possibly 50,000) as stated somewhere in the original manga.
The mistress of the palace, named Chimera, is a superhuman being too, gifted with magical powers and capable of turning herself into a giant Sphinx and her soldiers into flying, laser-breathing lions. Caral killed her brother and she wants vengeance, then she wants to capture Caral alive because killing him would "grant him a ticket to heaven".
Caral assaults the castle frontally and starts by tearing down the walls, one by one. One of the guards on the battlements reminds the others that received orders to take him alive.
On the contrary Caral is determined to cut his way through anyone standing in his way to the antidote: hordes of woefully outmatched guards pay with their young lives for trying to stop his murderous wake.
He blows up walls, burying many under the rubble. Once inside he mercilessly butchers the brave warriors by the hundreds with his magical sword. He crushes entire squadrons throwing blocks of collapsed fortification at them. He causes earthquakes and opens chasms into which dozens fall to their death.
At some point even a giant slug-like entity, then a tentacled eye and finally an army of golden statues, join the relentless massacre of the guards.
Caral shows no pity or remorse for the hundreds of lives he takes in order to save his friend: he slaughters the legion of helpless young female soldiers with total indifference. They are just a mere nuisance to a demi-god: they never stood a chance and all he cares about is to exterminate them quickly and efficiently, because he needs the antidote ASAP.
As fast as the brave warriors stream into the fight, he cuts them down. Dozens squeal and drop before the brutal work of his unquenchable blade! He leaves behind piles of gasping fallen. A plague of steel and blood descends upon the impossibly outmatched guards and when he approaches the tower they fight even harder, though not necessarily longer.
When Chimera's spell turns what is left of the army into flying lions (utter idiocy, by the way!) the carnage continues and the mutated warriors keep getting massacred by the dozens... until the conclusion of the story, in Episode 39.
Needless to say... I liked the anime and the manga, a lot! Unfortunately the rest of the series is quite dull, with apparently no other appearance of Chimera and her army of expendable female warriors, apart from a few gory pages in N. 21 of the comic book.
However, I can't help wondering why such sublime example of female Zako hasn't come out earlier on this forum... or elsewhere!