A cartoon I saw as a child in the 80s on British TV made a huge impression on me, but I've never been able to track it down online. It was a one-off short about a scientist who creates a robotic black cat. The cat falls in love with the image of a neon sign in the shape of a white kitten drinking milk, but when he climbs to embrace it, it electrocutes him and he dies. The end!
Some of the tropes remind me of Tezuka but I haven't managed to identify it. It seemed to be a one-off short rather than a series, and could easily have been American, Japanese or European.