Can you explain the whole Yumekawaii and Yamikawaii thing?
First of all, we should mention that both only settled for clear definitions within the past 6 months so articles before that time may be a bit wierd because authors often would confuse both for each other.
Yumekawaii (Dreamy Cute) was originally coined as umbrella term to describe everything featuring the typical girly pastel aesthetics. Lots of girls wear multiple fashion styles and mix them, therefore it made describing your style much more easier than saying “My outfit is a mix of Fairy Kei, Mahou Kei and Pastel Decora!”.
It basicly was all about the ideal dreamy pastel cuteness.
That changed when Yamikawaii (Sickly Cute) came to be - it is a wabi-sabi aesthetic focused on the imperfection and suffering behind the surface of exactly that kind of ideal but the colors are usually rather dark and only little pastel with lots of medical motifs.
After a while, the both of them would start to develop a ying-yang relationship, which we refer to as YCawaii, as they started to contain the rather subtle parts of each other, Yumekawaii would contain a little bit of Yami and Yamikawaii would contain a little bit of Yume.
tl;dr: In case of Menhera, everything in girly pastels falls under Yumekawaii while everything less girly and more dark falls under Yamikawaii!