I guess that the "g" means "gram".

I think so. I edited some notes.

Well it might be that Hinnuu being much more athletic might weight more due to muscle weight (Muscle is said to weight more than fat) and Arima strikes me as someone who doesn't have much muscle (but a decent amount of plushness chest and rear wise)

Why I am so fat...!
Why your weight is less than mine...!

Senka looks cute in a hoody.