What does A-kun buy only at a far convenience store, not at the one next to his house?

Ero-book?

The correct answer is an umbrella, haha. If he's next to his house, there's no need to buy one, right?

If a boy buys something at a place far from his house, of course it would be an ero-book!

Definitely an ero-book, I tell you!

Ero-book!