Yuzuyu
When we meet her, Yuzuyu has just been abandoned by her mother after her father's death and placed under the care of her cousin Kippei.
Yuzuyu's character is where the charm of Aishiteruze Baby lies. Youko Maki made her a very likable character that's also pretty realistic for a small child. She's very cute, sweet, and good-natured (the way a light-hearted series with a small child as a main character requires), but she's not sugary and shows some of the negative characteristics abundant in small children. For example, she can sometimes be selfish in sharing Kippei's love when she fears it might be taken from her, not realizing other people need him too. But getting to know Yuzuyu, it's easy to understand why Kippei's able to accept his responsibility toward her at the beginning of the story despite his initial reluctance.
Since Yuzuyu's a small child, she always refers to herself as "Yuzu" and to most older people as either "oniichan" or "oneechan" (both are terms of endearment for older brothers and sisters, respectively).