"Why do boys wear bags at all? All you need is money, keys, phone… right? Pockets in your jeans will do… Wrong! One obvious reason is practicability here! If you ever lived in Tokyo, one thing is for sure: everybody spends a lot of time traveling on the train from home to the centre of things (think about the greater metropolitan area of Tokyo - this is not Paris!). That’s why people might not come home after work before sports or party activities (and some won’t even come home for days…).
Therefore it does make a lot of sense to keep everything in one decent looking bag. Another thing is culture, I guess. Whereas in Europe boys are just fine to carry their uttermost essentials – maybe they like to feel free, unhampered from any exterior burden such as a bag - let alone the sight of a feminine looking handbag! A Western bloke wouldn’t so easily throw the strap of a small purse over his shoulder to head out in the urban wilderness…"