Lil late here but I have some japanese chicks the same age as yours were when these pics were taken. They all appear to be female except for the white one just going off the length back of the comb and the ridges, not sure though. I don't see red in its comb. Did it end up being a lil roo? I have two roos in my group now at 2.5 weeks old and they both have noticably larger combs than the others that are beginning to redden already.
My original group is from Ideal Poultry, you can see a million pics of em in my gallery, and these new chicks are from Cackle Hatchery. I'll post pics of them too in a bit.
I love Ideal and Cackle! I have an unusual bantam that came from Tractor Supply. It holds its tail straight up. Is it a Japanese too? I too need to post pics.