Manga like Grandoll

"Grandoll" is a science fiction story whose theme is the invasion of Earth, featuring a boy's fight against aliens from outer space. As part of their plot to invade the Earth, the aliens send a doll that transforms itself into a human to the Earth.

A junior high school student Utsuki Tetsuo, commonly known as Tecchin, is an ordinary boy without much willpower or ability to asset himself. One day on his way home from school he finds a girl's dead body on the street. While he goes to the police to report it, the girl's body disappears. Instead, he finds a strange doll there. Tetsuo brings the doll home and repairs the broken part. Then the doll instantly turns itself into the girl who appeared to be dead. It tells him that it is a "Grand doll," and that so is Tetsuo. A Grand doll looks just like an ordinary doll at first glance, but when rubbed on the neck, it turns into a human or a horse. When scratched on the neck, it becomes a doll again.

It is the aliens from outer space who are scattering Grand dolls around the Earth. Actually, it is part of their plot to invade the Earth. When Tetsuo learns about this, he becomes determined to fight against the invaders with the help of his father, a newspaper reporter, and Yoko, his friend, despite the fear that he may be a Grand doll as well.

(Source: tezukaosamu.net)