Translation guide
A theme song is a piece of music associated with a TV show, movie, game, or event. In Japanese, the most common and natural way to refer to this is 主題歌 (shudaika). There are also more specific terms for opening and ending songs, as well as related concepts like image songs and insert songs.
The main song associated with a show, movie, or game.
The standard, all-purpose word for 'theme song'. Used for TV shows, movies, anime, games, etc.
The theme song of this anime is very popular.
Who sings the theme song for the movie?
A loanword from English, also commonly used. Slightly more casual and often used in promotional contexts.
The theme song for the new drama has been announced.
Literally 'theme tune'. Can refer to instrumental themes as well as songs. Common for movies and TV.
The theme tune for this movie was composed by a famous composer.
The song played at the beginning of a show.
The song played at the end of a show.
A song associated with a specific character or concept, not necessarily used in the show itself.
A song created to represent a character or the world of a series, often released on character albums. Not used as an opening or ending.
This character's image song is sung by the voice actor.
Abbreviation of 'character song'. Very common in anime/game fan communities.
I'm playing my favorite character's song on repeat.
A song played during a scene within a show or movie, not at the opening or ending.
A song inserted into a specific scene, often used for emotional impact.
The insert song in that scene was really impressive.
主題歌 is the most standard and widely understood term. テーマソング is a loanword and feels slightly more modern or commercial. テーマ曲 can refer to instrumental pieces as well as vocal songs, so it's broader. In most everyday situations, 主題歌 is the safest choice.
Please tell me the theme song.
I get excited when the theme song plays.
In anime and game fan communities, it's common to abbreviate opening and ending themes as OP (オープニング) and ED (エンディング). You'll often see phrases like 'OPが神' (the opening is god-tier). These are very casual and mostly used online or among fans.