So I'm relatively new to figure collecting. I bought this kana figure (the red head in case anyone doesn't know.) which I love and obviously I need to get the other two members of the group so make a set.

I went on Amazon and found mem(the blonde one). And ruby which said they were frequently bought with this kana figure.

I have an issue however since mem is so much smaller then kana and I fear ruby will be the same.

How do I go about getting ones that are the same size or make sure they are from the same set. I'm not really sure what I'm looking for and googling this isn't helping since I keep pulling up results that are wrong or not what I want