Koibito-tachi no Happy Birthday is a CD exclusive song in the Love Series, appearing to concern the further relationship development between Sota Mochizuki and Akari Hayasaka. The song was first released commercially, as the coupling track in the single Heroine Ikusei Keikaku / Koibito-tachi no Happy Birthday released at Comic Market 96.
<infobox theme-source="series">
<title source="title1"> <default>Koibito-tachi no Happy Birthday</default> </title> <image source="image1">
</image> <label>Japanese</label> <label>Rōmaji</label> <label>English</label> <group collapse="closed"> <header>Song Information</header> <label>Released</label> <label>Length</label> <label>Lyrics and Composition</label> <label>Illustration and Movie</label> <label>Music</label> <label>Characters</label> <label>Sung by</label> <label>Album</label> <label>Single</label> <label>Links</label> <label>Counterpart</label> </group> </infobox>