Plastic Boy

When Sankichi Nakamura arrives to school late one morning, he discovers that there is somebody already sitting in his chair that looks exactly like him. After failing to convince the teacher that the boy in the seat is an impostor, he is sent on his way home.
Upon arriving home however, the same impostor is already there with Sankichi's mother pretending to be Sankichi.

Before long it is revealed that the impostor is actually Plastic Boy, an alien life form on the run from the police that can bend and contort his body into any shape he wishes. His plan? To seek refuge in Sankichi's house by literally replacing poor Sankichi!

Written in 1959 and published in Issue 4 of "Tetsujin Comics" this short story was written shortly after the the much longer "Plastic Man" which was published the previous year in 1958.

This now hard to find title was written by Mizuki Shigeru under the pen name "Azuma Shinichiro"