I remember borrowing my cousins' new gadget early in 1980. With the headphones plugged on my ears, I felt like a real dude.

But, browsing through Sony's pre-1979 catalogs makes one feel this wasn't all that new: there were portable tape players aplenty and many had about the same size and looks...
The TC-44 for instance or even the TC-50 that went high up into space ten years before the TPS-L2 was released.

What probably did it, besides weight (300 grams, as opposed to the 900 grams of a TC-44), market-wise, is that none of the previous portable cassette players were tagged WALKMAN - more a matter of concept than anything else, in proper Sony tradition.

Case in point: the TCM-100 was a recorder released in april 1978 - same size, same weight, same design - but it wasn't named Walkman... You can see the TCM-100 here.

The traditional WM moniker didn't come with the 1st Walkman because although it was planned to be a success, it wasn't expected to become such a success.

The TPS-L2 was rebadged as a WM-3 in 1981 (1982 world-wide) : same object but black, with the WALKMAN logo on the lid, success oblige. It should be noted, however, that only the early samples of the TPS-L2 didn't have it - quick success oblige!