Yotsuba&! manga volume 5 features story and art by Kiyohiko Azuma.

Yotsuba met a robot at Ena's house! Betcha haven't met one ever! It was THIIIIIS big - but not bigger than Jumbo or anything - and it ate money! Yotsuba's never met anyone who ate money before! Maybe it gets more powers with more money!? Yotsuba should try giving it more money next time! Huh... what happens when money-eating robots get full? Do they have to go to the little robots' room? Hmmmm...