Medusa (メドゥーサ) is a character who featured in Nobita's Great Adventure into the Underworld and its remake Doraemon: Nobita's New Great Adventure into the Underworld – The Seven Magic Users as one of the main antagonists. She is a demoness that serves the Demon King, Demaon.
Whereas the original film portrayed her as a minor demon, her role in the remake is greatly expanded, where she is now revealed as the corrupted form of Miyoko's mother, Ms. Mangetsu. She made a deal to Demaon to save her daughter, but at the costs of having her soul taken away by Demaon and being transformed into a demon.
Nobita's Great Adventure into the Underworld
In the original version, Medusa is a skeletal-looking demon with hair full of snakes sent by Demaon to hunt down and dispose of Doraemon and Nobita. It chased them through the time tunnel back to the original world and petrified them. After they fell into the tree at the Open Lot, it returned back to the present time and was never seen again afterward, presumably destroyed after Demaon's demise along with the Demon Star.
Nobita's New Great Adventure into the Underworld
Medusa was once a normal woman who married with Prof. Mangetsu and together have a child in which they named Miyoko. For a long time, they lived happily until the day Miyoko mysteriously became ill due to a deadly disease. Sadly, there's no cure for such disease. Mrs. Mangetsu then decided to seek the ancient spell from an ancient book to save Miyoko without hesitation out of desperation, and came up with forbidden spell where one would surrender his/her soul to Demaon in exchange of their wishes granted. When Prof. Mangetsu discovered this, he was horrified and warned her about other consequences that would happen.
Unfortunately for him, Mrs. Mangetsu used that spell anyway, resulting in her getting summed by demonic flames and taken away by Demaon. Prof. Mangetsu tried to stop this, but it's too late though Miyoko was eventually cured of the disease.
Events in the film
Gazing through his crystal ball, Demaon witnessing Doraemon, Nobita, Suneo, Gian, Shizuka, and Miyoko would come to foil his plans. So, he sent Medusa to see how powerful they are. He also sent the Monkey Demon both as her companion and to keep an eye on her in case something goes unexpected on her.
Medusa made her presence known to her former family by destroying her former home with a pillar of light. Though they survive the mystical blast, she had a demon to capture Prof. Mangetsu whilst cursed Miyako into a cute-looking mouse (Nobita and his friends managed to tamper the curse by making her turn into a cute anthropomorphic cat instead later on), before posed as her to manipulate Doraemon and co. She played the ruse well as when she fought against a remaining demon soldier who showed up and tried to kill Doraemon and Nobita (though in the fight, it was Doraemon who defeat the demon in the end). Once she and Doraemon and co. gained the possession of Nirnaeth's scroll, she removed her disguise and buried her enemies under a conjured avalanche. Fortunately for Earth, Medusa only gained half of the scroll, which resulted in her being punished by Demaon.
After the ill-attempt to assassinate Demaon, Medusa quickly followed Doraemon and Nobita through the time tunnel and managed to catch up. She emerged from Nobita's desk and chased them through the sky of Tokyo. After a quite troublesome chase, Medusa petrified Doraemon and Nobita which the former fell back into Nobita's room while the latter into the tree at the lot. Succeeded in her mission, she returns back to the present time.
Demaon then gave Medusa her final mission, to destroy the seal on the moon in order to finally allow the demons to invade Earth, knowing that despite her resistance toward the magic of the moon, she will perish when the seal is destroyed.
By the time she goes to destroy the seal and Doraemon and co. showed up, something unexpected happened: Miyako's voice as she begged Medusa to stop caused Ms. Miyako's humanity to resurface, which made her briefly lose her identity in spite of her ability to resist it enough to destroy the seal. By the time the seal of the magic of the moon destroyed, the released energy not only killed Monkey Demon, but also destroyed Medusa's demon persona and free her original human psyche as she reverts to her former human form. Prof. Mangetsu and Miyako were horrified with this, she then collapsed, and became weak. And as they held Mrs. Mangetsu, Mrs. Mangetsu revealed that because her soul was taken and turned into
a demon, the loss of her demon part made her cannot exist in her human form for long. In her last breath, she revealed that Demaon has put his heart into the red moon of Magic Planet, which explained the first attempt to killed him failed, she then encouraged Miyoko to be strong, Miyoko tried to hug her, however, she disappeared by breaking into pieces, the spirit flew up to heaven after that, then her locket fell to the ground, with the remnants of the golden light in the locket flying up to heaven as well. then Miyoko kept it, saddened by this, but with support, she then keeps fighting
with Doraemon and Gangs' help until they finally killed Demaon. After that, suddenly, the locket of Miyoko's mother flashed a beam of golden light and the locket disappeared forever, which healed the moon, protecting the Earth forever. This legacy of Mrs. Mangetsu shows that actually she was forced to be an evil demon.
- Her name along with her appearance is similar to the greek mythology with the same name "Medusa".
- Medusa's original name in the remake is not revealed, only that she shared the surname of her family.