Doraemon vanishes, and for one perfect episode, the show becomes about what you lose when the magic leaves. The comedy doesn't disappear with him, it shifts into something warmer, something about a kid realizing his best friend is irreplaceable. That's the whole trick: make you laugh at the chaos, then break your heart with how empty it all is without him, then let him come back and prove that the bond was never about the gadgets at all.
Kaettekita Doraemon is a comedy special released in 1979. The entry consists of a single episode rather than an ongoing series, and its listed genre points to a lighthearted, humorous tone.