Maybe it's another way of showing that Fai's not Japanese, like the sushi, not knowing kanji, and etc. I think there was a point about how he made sweet food for breakfast which irritated Kurogane, since that's not the traditional Japanese thing.
anyway we just have to look at Fai to know that he isn't japanese,blond hair and blue eyes are not very common in this countryÂ
but there has been many hints that makes me think that Fai has european origines,starting by his name,"D.Flourite",which sounds very french!i can tell you since i'm french myself,and not any others countries use these letters to make this kind of pronunciationÂ
!
next Fai is a fine cook who loves to compose specialities culinary with sweet and subtle ingredients,which indicates that he has very refined tastes,and presicely french cooking is appreciated thanks to his famous gastronomy!spicy meals are not our cup of tea,we prefer honeyed flavoursÂ
to finish Fai is addicted to alcohol as much as he seems to be exalted by milk,and again France is as much well-known for his productive agriculture and wonderful campaigns than for his inestimable wineÂ
i'm not saying that Fai is definitely french,but at least it gives me hope (Fai would be a perfect representation of french peopleÂ
)