He was originally a hostage who was sold to a laboratory by his relatives. He wanted to escape but accidentally ate a failed experiment and transformed back into his five-year-old self.
I thought I couldn't escape, but I met Mr. Tang who came to visit the class, so I was picked up and taken home.
However, when he finally regained his appearance, he returned to his true nature.
"Be good and call me husband."
"I don't! I want a father not a husband!"