Sarashina Kyusuke
Kyusuke is a pain in Chibiusa's neck from the time that she starts elementary school in fourth grade. His parents run a Soba shop and he's always making a nuisance of himself and pestering Chibiusa and Momo. Still, he is pretty darn brave, and he does really like Chibiusa. In fact, he may have a crush on her for a while, although later on in the manga it's implied that he and Momo may be an item.