Miyoko Mangetsu (満月 美夜子 Mangetsu Miyoko, alternative spelling: Miyako Mangetsu) is a character that appears in Doraemon: Nobita's Great Adventure into the Underworld and the 2007 remake of the movie. She is the daughter of Professor Mangetsu.
Miyoko lived with her father Professor Mangetsu and her mother happily for a long time. She was happy with her mother till the day she mysteriously became ill. The illness had no cure. Trying to save her daughter, Miyoko's mother made a pact with Demaon through a forbidden spell. Miyoko's father was unable to stop her in time.
She lived with her father and became a master of magic and carpet riding. Eventually, when she met Nobita and the others, she was turned into a cat (a mouse in the 2007 movie) by dark magic and her father was captured. Luckily, Nobita and the gang freed her from the spell and helped the Professor escaped, but were caught by Medusa, Demon's assistant who was traveling to the moon to destroy it. She eventually destroyed the moon, causing chaos to roam across Earth, but after Medusa saw Miyoko's face, she remembered her past and her evil body was melted, revealing Miyoko's mother. She died while telling Nobita the secret of defeating Demon. Finally, Doraemon and his friends defeated him. Suddendly, the locket of Miyoko's mother flashed a laser and healed the moon, saving the Earth forever.
- Nobi Nobita - it is implied throughout the movie than Miyoko has some crush on Nobita. She also encourages him that he is the only one who can save everyone.
- Shizuka Minamoto - They are simply friends.
- Doraemon - Doraemon falls in love with Miyoko's cat form.