Board Thread:Off Topic/@comment-25396609-20160205040608/@comment-26397825-20160210023141

You know, 120lbs is within healthy weight for a 5'6" female, so she's not really painfully thin.

Also, painfully thin usually implies some form of anorexia, even if it's not severe, and can lead to major problems such as lethargy, fatigue, muscle weakness, bone weakness, inability to concentrate and that sprt of thing. Not exactly the type of things you want your Huntsmen to have. Any school worth their salt would have immediately put her on a dietary regime designed to keep her weight within healthy range and avoid those problems before she ever got to Beacon. They wouldn't focus on buffing her up or anything, they'd simply focus on keeping her healthy enough to succeed as a Huntress. It is an important job that is focused on the defense of mankind as a whole. There's most likely a minimum weight depending on height, if only to make sure you're not at risk of anorexia.

If you want a skinny girl, describe her as lithe or slim or petite. Not painfully thin.

And the name....yeah. Tin on it's own is okay, but Miasma is a terrible last name and it sounds like you only picked it because she creates a poisonous cloud as her semblance. If this is the case, that's aterrible reason to choose a name. Pick something unassociated with either her weapon, fighting style or semblance.