how tall is Yukine?
According to this chart, Yukine is barely bigger than Kuraha as a lion:
And how tall is the average male lion? At the shoulders it’s around 3.9 feet. So on average he’s probably a little bigger than four feet.
And if Yukine is barely bigger than that, it means he’s under five feet. Yukine is four foot something. He is a tiny little boy
This is made more believable when you consider that the average japanese woman is around 5′2 and the average male is 5′7 ½.
Side note; the wiki does say that Hiyori is 5′6, but I find that a little hard to believe. If she’s already two inches taller than the average woman in middle school, why hasn’t she been scouted by the basketball team? Not to mention she’s grown as the manga has progressed (as pointed out by @hafuriyuki) So by now she’d be at least 5′8.
In conclusion: Yukine is a tiny boy, Hiyori is not taller than me, the wiki heights (which aren’t cited) are wrong and @yatorihell can fight me.