For a song titled "Joy", the melody admittedly doesn't sound really all that joyful. It's quite melancholy, in fact. This was a track from singer-songwriter Makiko Takada's（高田真樹子）debut album "Makiko first" from 1974, and despite the sadness imbued into the melody (with the first words sung by Takada being "Sayonara, sayonara..."), it's still a lush and very 70s musical experience. Mitsuo Hagita（萩田光雄）arranged everything and it does sound rather epic coming in through the headphones.
Musician-songwriter Kentaro Haneda's（羽田健太郎）piano really makes an impression and he's ably assisted on "Joy" by folks like drummer Hidekazu "Ponta" Murakami（村上 “ポンタ” 秀一）on drums and Masayoshi Takanaka（高中正義）on guitar. I was getting all sorts of Carole King and Joni Mitchell vibes as I was listening to "Joy". There are a couple of other tracks that I've already covered from "Makiko first": "Watashi no Uta no Kokoro no Sekai"（私の歌の心の世界）and "Blues Singer".