Mass manipulation is the ability to alter one's own physical mass and size.
- Sylvia possessed this ability naturally.
- Billie Masahashi will have this ability naturally too.
- Gabrielle Cooper has this ability naturally.
Sylvia can only use this ability on herself. She has been shown growing large enough to wreak havoc through a city and throw cars, and shrinking small enough to evade bullets and hide behind a coin. Her clothes also grow or shrink with her, but nothing else does.
Billie will be able to alter her own mass. She will be able to grow to a gigantic size and also shrink until she is minuscule and barely visible. Her weight and strength will vary accordingly. Her clothing and shoes will change size with her, as will any object she is touching or carrying at the time, but she will not be able to alter the mass of animals or other people even with contact. Her ability will be derived from her aunt's ability of growth manipulation.
Gabrielle can alter her own size and mass, but cannot change others. She can grow to an enormous size, resembling a giant, and can also shrink until she is barely visible. Her clothes alter accordingly. However, nothing else she is touching or holding will change in size with her.