@Destynova
So, she is 189 cm and is in middle school? That would make her about 14 years or so. According to a wikipedia article on height by nation the average height of a Japanese female is about 156-158, so that would make Hiki over 30 cm higher than average and since she is still in puberty she is likely to continue to grow. I can understand her concern for her height, but when you are that tall at such a young age there are usually some medical condition causing it.
Doesn't have to be medical though - Average height 2015 for a 14 y o girl in Japan was 156-157 cm https://nbakki.hatenablog.com/entry/Girls_Average_Height_and_Weight_by_Age_in_Japan
But by standard deviation (on the same page) if it is by inches (as it should be) then at 189 cm she clocks in at just below 2.5 standard deviations, meaning one out of 81 Japanese 14 y o girls can be expected to be about 189 cm tall.
tl/dr, she seems to merely qualify as very tall, but not extremely tall / unique. And the age span of 14 is (IIRC) the one where girls are most likely to be taller than the boys (since they're about finishing their growth spurt, while the boys are just about starting theirs)
That said, even shorter asian girls (merely "tall") have problems, so I can see her giving up over it https://medium.com/@joannalai/11-things-to-know-about-being-a-tall-asian-girl-46c10605b55a
(Other tall girls will often end up with a kind of scrunched up walk, since they can't stand being so much taller than everyone in class)