Jinrui Hatsu no Uchuu Sensouka?! Michi to no Souguuki

Overview

Nobita's father dreams that his father tells him to be strict with Nobita so he gives Nobita a hard time. Nobita and Doraemon travel back to the past and find Grandpa is very strict but secretly has a heart of gold. They explain to him and he goes 30 years to the future to tell dad to be kind to Nobita.