For your viewing pleasure, apparently the existing breast classifications were insufficient to accomodate our latest mahjong heroine's breast size. So they created a whole new class for her.
I have always wondered if Nodoka actually wears a bra... it really doesn't look like it. I could be wrong you know...
... and I finally realized what the penguin was for. It was for breast support to ensure she does not tire from fatigue after long hours of being weighed down by her oversized mammaries.