Perhaps they saw a very charming customer. It could be someone with an alluring appearance or a very polite and charismatic demeanor that made the girls blush.
In fanfiction, it might be due to some special event in the shop. For example, a surprise gift delivery for the shop girls. Or maybe a famous person related to the EMIYA England shop made an unexpected visit. This sudden excitement could lead to them blushing.
They might be described as having rosy cheeks and a shy look in their eyes. Their smiles could be a bit more coy than usual.
Friendship is a very common theme. These fanfictions often show how the wizarding girls support each other through tough times in the magical world. Another theme is the discovery of magic. Since they are in England, there could be unique magical elements that the girls find out about, like old spells or magical artifacts specific to the region.
One possible plot could be that Kuro and Emiya meet in a mysterious realm. They are initially suspicious of each other but then realize they share a common goal, like saving the realm from a dark force. So, they team up and use their unique abilities to fight the evil.
A popular one is 'Among the Wizarding Girls of England'. This fanfiction follows the daily lives of the wizarding girls, from their time at Hogwarts - like classes, Quidditch matches - to their adventures outside the school in the wizarding villages of England. It's a story full of magic, friendship, and a bit of young love.
A plot could involve Shirou being transferred to the Highschool DxD school. He quickly catches the attention of Rias and her peerage. His different style of combat and his unwavering determination might lead to some friendly rivalries within the group. He could also introduce some new concepts of magic that the DxD characters have never seen before, like his ability to reinforce objects. And he may find himself in the middle of the power struggles between the different factions in this new world.
Well, perhaps they meet in a bustling city. Emiya is drawn to a strange energy which turns out to be Chloe. At first, they misunderstand each other's intentions. But as they start talking, they find out they both have a connection to a certain magical artifact. This leads them on an adventure together to find and protect the artifact.
Well, perhaps they are at a park. Haru is feeding the ducks and he looks so gentle and kind while doing it. The reader watches him and blushes at his soft side. Haru then offers the reader some bread to feed the ducks too, and as their fingers touch, the reader's blush deepens.
One possible plot could be that England, as a girl, might start exploring her new identity in a modern world. She could face challenges in adapting to the social norms for women while still carrying the historical and cultural essence of England within her.
One possible reason could be for adventure. Hermione is a very curious character. Maybe in the fanfiction, she has heard of some mysterious magical place outside England that she just has to explore. For example, there could be a hidden library full of ancient and powerful spells that is only accessible in a far - off land.
Even fictional characters from English literature could be involved. Sherlock Holmes could be brought into the story to help solve any mysteries that might arise due to England's transformation. He could use his deductive skills to figure out the cause and consequences of this strange event.