Doraemon: Nobita's Three Visionary Swordsmen (1994, Shin-Ei Animation)

Nobita dreams of himself as the swordsman hero "Golden Hat" one night only to be waken up late for school again. When he remembers he hadn't done his homework yet, a strange man appears and lets him have a "Cherry of Knowledge. Nobita completes his homework without a problem but the effect doesn't last for long. Soon, he meet the man again...