Doraemon Birthday Special: "The Giant Midnight Dora-Tanuki"

To have a good memory of the last days of the summer holidays, Nobita and his gang build a cabin in a tree. The next morning, however, they find her devastated. Friends decide to set traps around the tree to capture the person responsible, which turns out to be an alien leech that parasitizes its victims and turns them into giants that devour everything, capable of destroying entire planets.