Japan average height of males: 171.2 cm (5' 7.4") and females: 158.8 cm (5' 2.6"). She's even a giant among men, and he's a shrimp amongst women.
I couldn't help but be reminded of that other series where the female kouhai bullies the male senpai, but in one chapter this is already so, so, so much better. Unlike that other Senpai, this Senpai has a backbone and doesn't put up with the bullying.
@liquidsword @Cakexx I did not get the impression that they are boyfriend and girlfriend, though she seemed to imply that they were childhood friends, which would make sense of why she so free and easy with him since she's two grades below him.
@JasmineTea Thanks for the scanlation and, yes, please continue!