Mei was expressing herself directly to Yuzu. Several times through normal conversations, before she finally went to ask Harumi for assistance.
Yuzu just didn't listen to her seriously. She heard the words, but didn't act on it. Even Harumi had to be pretty aggressive to get the message through to Yuzu and literally force her to look at herself in a mirror.
Also, it was good progress for Mei to talk with Harumi. They never really communicated directly before, and Harumi's mirth about Mei's rather cute request was amusing. Her image of Mei seemed to change quite a bit.