character song; character theme song
A song performed in-character by a voice actor or associated with a specific fictional character, common in anime, games, and idol franchises.
wasei-eigo (Japanese-coined English), from character song
The character songs for this anime are sung by the voice actors themselves.
I listen to my favorite character's theme song every day.
Variant with interpunct; less common in running text.
Wasei-eigo from English 'character' and 'song'. The term is not used in English with this exact meaning.