Sharp doesn't make mechanical pencils, so far as I know. I'd also be sort of surprised if Panasonic made lightbulb sockets.

To your broader point, though, it's true that most of the major Japanese conglomerates have amusing/modest origins and have accrued side-businesses over time until they became goliaths.

It's still interesting that a company like Panasonic began with something so mundane. Other than a few cases like IBM (which began as separate companies making time clocks and card punchers), it's not that common a story in the western market.