Harmony Day

is a song by Morfonica.

It is the title track for their 3rd single, with Sonorous and Fateful... as the coupling tracks. It was released on October 6, 2021. The limited Blu-ray edition included recorded footage for both Special Live ~Summerly Tone♪~ (Morfonica PART) and Cantabile.

It is the gift song for the event Einsatz of A New Journey.

It was written by Oda Asuka, and arranged and composed by Fujima Hitoshi.

Chart Performance

 * The single reached 9th place in Oricon's weekly Singles ranking for the week ending October 18, 2021.

Live Performances

 * February 23, 2021: Astral Harmony
 * May 21, 2021: Andante
 * September 4-5, 2021: Mythology
 * October 28, 2021: Amabile at Zepp Osaka Bayside
 * November 5, 2021: Amabile at Zepp Haneda