"Passion") is a song recorded by Japanese singer Shizuka Kudo, from her twelfth studio album, Dress.

Nakajima's lyrics invoke the series' title, which loosely translates to "Unyielding Night".

Nakajima writes about a protagonist having to face adversity in love because her lover is romantically committed to someone else.

In 2014, Momoiro Clover Z performed the song with Kudo on the CX variety show Shin Dōmoto Kyōdai.

[5] That same year, Tomomi Kahara performed "Gekijō" in duet with Kudo on the CX music show Atashi no Ongaku.