Cesare actually feels very similarly about Rika. He has his own deal with classifying people as in or outside of his circle, too. :') Rika isn't in it. But he is perfectly capable of being polite to people he doesn't have real ties to and it's nice to know some interesting people who he's not really involved with. Also, Rika appears to be around the same age as his sister, so that gets her some points in her favor. :D