Feiko is a boss from the completed, but unreleased, NES video game Secret Ties (怪盗シュガー).
She is an evil lookalike of the hero's kidnapped girlfriend Reiko, she has a convincing enough apperance that the hero thinks that she actually is Reiko until he gets very close to her. She first appears in a staged kidnap scenario in fake chains, and then attacks the hero when he gets close to her. Before she attacks, she tells the hero:
"Reiko belongs to us now!! But don't you worry, I'll put an end to your misery!! Ha, ha, ha, haaaaa..."
She attacks by punching and kicking, which includes a slide kick across the floor. Her final attack is her jumping in the air towards the hero ass first, which damages you when she makes contact.