The story arcs aboard the Straw Hat Crew's first ship Going Merry (Merry Go in some adaptations) are recreated with brand-new animation, from Luffy and Usopp's fight and Robin's disappearance to the crew's final farewell to the ship. Going Merry is treated as another member of the Straw Hats as Luffy, Zoro, Nami, and the rest of the crew set sail for the legendary treasure, the One Piece. (Source: ANN)

Jealous of Suneo's new robot toy, Nobita asks Doraemon to build him an even better one. Doraemon initially refuses, until Nobita accidentally discovers pieces of a mysterious robot that falls from the sky. After gathering all the robot parts and assembled them together, the giant robot, Zanda Claus, is soon completed. The duo soon learn that the robot is not a mere toy, but a powerful weapon in the fight against the coming Robot Army that is going to attack Earth and enslave the human inhabitants of it. An invasion is near, as a mysterious girl Riruru (リルル, Alternative spelling: Lilulu, Lillele [Doko Demo Doa Scanlations]) shows up, looking for the robot. (Source: Wikipedia)

"The time of destruction is coming ever closer without a doubt. It cannot be stopped." To know death, to gaze at death, to face death. Makoto and his allies have grown through the many meetings and partings they have experienced. Their fight might not be for the sake of the world, but for themselves. Even so, they have continued to fight, believing that there are peaceful days waiting at the end of the battle. However, a boy says that destruction is the fate that humanity must shoulder. The boy they believed to be their friend tells them the truth of the situation without an emotion on his face. The season changes to winter. Makoto makes a decision in order to greet the spring that is waiting beyond... (Source: ANN)

OVA episodes bundled with the 8th and 11th volumes of the manga.