"When a Rainbow Appears" is featured as an insert song on Kiyoshi Maekawa's Egao Manten Tabi Zuki. Originally written for Kiyoshi Maekawa, this fan-favorite track is now reimagined through a heartfelt self-cover by Hiroki. With his warm and gentle vocals, the song has been reborn and is finally available on CD and digital platforms, answering long-standing fan requests.