Gusuke is a supporting protagonist in the When Phineas meet Nobita series.
Gusuke was born as the only son of Icarus, a famed hero of Birdpia, and a woman named Odia. One stormy night, while flying with his wife and his soon to born son home, Gusuke hatches from his egg and is almost blew away by the wind. He manages to catch on one of his father's feather but the wind is too strong and blew him away along with the feather, leaving his parents in despair. Fortunately, he was saved by a woman who is hiding from the storm under a tree trunk. She later takes him into her family which consisted of her and her husband and names him Gusuke.
Gusuke grows up to be an adventurous and inventive boy. He befriends Milk, a girl who lives next to him and they often go to school together. However, the thunderstorm left a lasting psychological trauma on him, causes his fear to fly.
Doraemon and the Winged Braves
Gusuke was fall when his plane was flying to human world. There, he meet Doraemon, Nobita and Shizuka. He introduces himself to them. Doraemon, Nobita, and Shizuka help Gusuke fix his airplane, where Nobita becomes fast friends with him. As Gusuke departs to his home, Gian and Suneo catch him and grab his plane. The other three follow them through the portal.
Arriving at Birdpia, Gian and Suneo are captured by the raven soldiers and brought to Commander Seagrid, who plans execution for them. Meanwhile, Doraemon, Nobita, and Shizuka find Gusuke near Professor Hou's house. Hou explains that Birdpia is a world that is far away from human world and is connected only during the bird migration, which is guarded by Bird Migration Patrolling Troops. Seagrid was once a member of the troops, but he was shot by humans and retired shortly, seeking vengeance at them. After Hou advises them to take cover as not many humans are liked in Birdpia, Doraemon brings "BirdHat" which can sprout wings by wearing them. The three and Gusuke manage to plan a rescue of Gian and Suneo shortly thereafter. Gusuke informs Nobita and his friends that there will be an annual competition, "Rally Icarus", which is used to recruit members of the Patrolling Troops, and that they should join it. During a dinner with Gusuke's parents and his friend, Milk, Gusuke confesses that he is actually adopted and that he is unable to fly naturally due to the trauma of falling he got before being founded. Meanwhile, Hou translates an ancient Birdpia tablet which contains information about Fenikia, an ancient being who can bring destruction to the world.
During Rally Icarus which takes place at a giant tree called the Perched Tree, Gusuke manages to win but is disqualified due to him being unable to fly naturally. The group later realize that Hou is missing and after Doraemon learns about Fenikia by reading the tablet using Translator Jelly, to search for Icarus, a legendary birdman who was imprisoned in the Birdpia prison after being falsely accused of getting Seagrid shot. They manage to convince him to stop Seagrid from awakening Fenikia, who is buried at Mount Rara Ato. Along the way, they find a projector which projects a hologram of Mamoru Torino, a 23rd-century Ornithologist who is obsessed in creating a safe haven for birds, which eventually led to the creation of Birdpia, an alternate timeline of the human world. However, the group is too late to stop Seagrid as he successfully awakens Fenikia. The creature does not follow Seagrid's bidding, and as it rampages in Birdpia, Gusuke awakes his ability to fly and manages to lure Fenikia to the top of the Perched Tree, while Doraemon and Nobita travel to the top of the tree where Mamoru's time machine is located, intending to harm Fenikia. While it doesn't work, they instead transport both the machine and Fenikia back to billions of years in the past, before the Earth is even created.
Celebrating the victory over Fenikia, Gusuke is revealed to be Icarus's son and he is given the position of Captain of the Bird Migration Patrolling Troops. Nobita and his friends bid farewell to Gusuke before returning to their home world.
Became a Rebel
Two years later, Gusuke, Milk and people from the Birdpia come to visit their friends. He meet Nobita again, and both are happy. Luke Skywalker introduced himself to him, and tell them that Emperor Palpatine is going to attack the Earth. Gusuke became a Rebel.