Yumiko is the heroine of the story. She is spunky, sweet, and straightforward, yet poignantly cute and unsure of herself when it comes to boys. When she loves, she doesn't even think of hiding it; her affection for her dog and for her Toshi-chan are right out in the open for anyone to see. She is what others would call "a breath of fresh air" - always fresh and cheerful, and completely honest, with herself and others.
	Handsome, black-haired Hamao Toshi is a newcomer to Yumiko's school. Like Yumiko, he has a very good memory, although he may not want to admit it. He is polite to others, but disliked being called Toshi-chan by Yumiko. He's easily miffed by her, and hides his feelings much better than she does - but he turns out to be just as kind and generous as she is, deep inside.
	Kuboi is another boy in Hamao's class. He initially makes moves towards Yumiko, giving her presents and such, but didn't seem too disappointed when she pursued Hamao. (He gave her a jack-in-the-box for a present, a box with a clown's head on a spring inside. It pops out when the box is open. It scared Yumiko, which amused Hamao greatly.)
	Aniline and Acetanilide are the names of the dogs in the story; both of them are Yumiko's well-loved pets, given to her by Hamao. Aniline is white, and Acetanilide is grey; both of them are about the same size (an armful), have large eyes, pleasant personalities, and ribbons tied around their necks.