Since she appears in all three shows, is possible that Haruko, who isn't human, is some sort of immortal or just lives longer and ages slower than humans do?
I'm guessing it's just her alien life cycle, if she even has one. For all we know, she's always going to look 20-something and just keep changing her style.
I believe That Haruka Haruhara became a immortal by using the terminal core while in space
What do you think?