On which we find out what Hisa’s been up to on the previous episodes. Also, the plot thickens! … sort of.
The sob story played out at the restaurant is based on a famous japanese story, “One bowl of plain soba” (Ippai no Kakesoba). It was a hit at the beginning of the nineties, and it spawned a book and a movie. The story tells the tale of a poor family who’d go to a soba restaurant and order one bowl of plain soba, while lamenting on their father’s misfortune. Back in the early nineties, the story was a big hit in Japan – not so much now with the invention of instant noodles, though! Here’s a recollection of the story, and here’s a translation of the original story. As a fun fact: according to JapanTimes, the guy who wrote the original story was later arrested for fraud.
J-Drama fangirls will immediately recognize Oguri Shun as Baquas, the armamentalist. His spell, Luffme, doesn’t appear to be an actual Dragon Quest spell; according to some fans on Yahoo Answers Japan, Luffme could be a reference to Luffy from One Piece, since Baquas’ clothes do resemble a pirate’s, and the spell’s purpose is to get his enemies to become his allies, very much like Luffy does with the power of ~friendship~.
As you may have pierced together by looking at the OP the past nine episodes, the Demon King’s Castle is actually a modern-looking city – to be specific, the city of Odaiba. A lot of japanese anons on 2ch jokingly commented at the time on how this could be a deliberate location choice: TV Tokyo’s rival network, Fuji TV, has its headquarters in Odaiba.