In the last chapter of the Refrain Blue series, the bond between Yoshihiro Matsunaga and Nao Morisawa grows stronger, while Yoshihiro finally finds out the identify of the mysterious girl from the first chapter.
| Actor | Role |
|---|---|
 Katsuyuki KonishiYoshihiro Matsunaga (voice) | Yoshihiro Matsunaga (voice) |
| YYumi KikuchiNao Morisawa (voice) | Nao Morisawa (voice) |
 Mie SonozakiMikage / Mysterious Girl (voice) | Mikage / Mysterious Girl (voice) |
 Ruri AsanoYuori Kawana (voice) | Yuori Kawana (voice) |
 Ai UchikawaShizuka Hayase (voice) | Shizuka Hayase (voice) |
 Shizuka IshikawaChinatsu Iwasaki (voice) | Chinatsu Iwasaki (voice) |
 Mari AdachiTsugumi Tsugashima (voice) | Tsugumi Tsugashima (voice) |