I'm starting to get annoyed by mc. I understand the hesitation from using your sister as reference. But if he really aims to be a pro, he should really research real boobs more. If it's that hard to use your sister, at least research using 3d porn.
@zerio I suppose it's not totally unheard of for an artist to want to stick to his own mental images. Mobuyuki seems like that. He's always doing everything without references, until he has got stuck for a long time and a solution (reference) is more or less forced on him. Only then he can willingly use it. It's hardly good for him, though, as a very fresh professional artist (since he doesn't have a really unique style). On the other hand, that attitude could allow him to write better stories. Stories are ruined by listening to complaints and feedback too much.