Translation guide
A portable cassette or media player, originally a Sony brand. In Japanese, it is a trademarked name commonly used generically.
Walkman (Sony brand)
Referring to a portable audio player, especially the classic Sony Walkman.
The standard term, derived from the Sony brand. Used for both original cassette players and later digital models.
Generic term for any portable media player, not brand-specific.
I bought a new portable player.
ウォークマン is a registered trademark of Sony, but it is often used generically in Japanese to refer to any portable cassette player. For modern digital audio players, ポータブルプレーヤー or specific terms like iPod are more common.
彼はまだウォークマンでカセットテープを聴いている。
He still listens to cassette tapes on his Walkman.