Rumour: The Philippines can be seen in Episode 01 and the first chapter of volume 1. She is a maid that serves Spain coffee at the conference.
Fact: False. Though some fans have speculated that the maid was meant to be an uncredited cameo of a Philippines character, the maid was intended to be a normal human and is simply credited as "Maid" in notes and in the anime guide WorldWideWalking. When asked by a fan who she was, Himaruya himself clarified that the maid was a Spanish housemaid; her brown hair and green eyes were like Spain's and are highly unlikely physical traits for a representation of the Philippines.
Proponents of the Philippines theory believe that she was not named due to controversial stereotype of Filipinas as maids, though the truth is that a character for the nation has yet to be introduced in the series. While it seems unusual for there to be a non-nation character at the conference, the series has shown instances of the nations interacting with normal humans before. In some cases, the humans are shown to be aware (in varying degrees) of the nations not being like them, and address them by their nation name (e.g., a pharmacy clerk referring to Germany as "Mr. Germany").
Rumour: Philippines will be a girl and her name is María Clara Fernández Carriedo (or "Clara De La Cruz"), and will appear in Season 3.
Fact: False. Though a fan-created character named María Clara exists, there is no canon Philippines so named. Though Filipino fans want a character for their country in the series, there has yet to be an official design. There have been hoaxes purporting this and the above rumour as fact, sometimes started by fans longing for an official character or trying to find significance for the conference maid or Asia3. There has also been no such news reporting of a Philippines in the third season, except for another fan-created hoax. Fans gave a shortend version of her name; Piri-tan.
Rumour: Asia3 is the Philippines, as Himaruya claimed she was close to America and had a complicated love story.
Fact: False. "Asia3" was shown to wear an outfit that some fans believed to be a maid dress, though the sketch was messy and the quality was not clear enough to tell exactly what kind of outfit it was. A later series of blog sketches revealed that the female character was actually intended to be Vietnam with an alternate hairstyle. Hoax-starters will attempt to earn others' trust by claiming that there was information about her that Himaruya deleted, but the fact is that there was no information aside from the vague sketch. Though Himaruya has deleted information in the past, they were only on old pages of his site or his short-lived Yahoo blog. In later years, fans have become better at archiving information and images in case of future deletions.
A falsified screencap was created and posted to the Hetalia Philippines community on Livejournal, stating that Asia3 would be Philippines, though it was discovered that the grammar did not match Himaruya's, the text appeared to be pixelised and the timestamp matched that of another blog post. Nonetheless, some continue to believe in there being some sort of conspiracy theory about a Philippines character.
It was later revealed in a series of blog sketches that "Asia3" was actually Vietnam with her ponytail worn differently. In the sketches, Vietnam was shown with various different hairstyles including one with a bun and one with flowers like the chibi sketch.
The Filipino fandom/comunity would love to have a character for their country, but that is still being decided upon. Though, Himaruya has stated that he would like to do the ASEAN countries some time. You'll never know!
On the top left, you see a dark skinned, darker haired male wearing what seems to be a Barong Tagalog. Keep your eyes open, we may have a Philippines design!