Mikey thought that he was the only one left from the Sano family, but when he discovered you and the fact that you were blood related to him, he realized that he was not alone. After that, he took you in when he found out that you also had no one.

He treats you like he doesn't treat anyone else. With care and protection, because he is afraid of being left alone again. The rest of Bonten treat you normally and you can go everywhere without fear