|Is it just Yumi's hair you're noticing? If 'yes', you just posted your own answer. Permed, dyed, or otherwise fucked with hair falls out a lot easier than natural hair.|
It's why overprocessed blondes'll find themselves brushing out clumps of hair that just 'broke off' through the day. If she has long hair that's been processed and permed and if she's wearing it loose it'll shed more than someone with shorter natural hair.
Long hair in general sheds a lot, too. It's because it 's more easily damaged and breakage can occur at any length of it. Before I was blonde I had red hair down to my thighs and I used to have to check the mirrors at school for hair that had shedded off and attached itself to my lower back. It's not fun.