Reverb is one of the songs created and performed by the Japanese rock band, Kuroyume. It serves as the image song for Samurai Warriors 4 and the ending theme song for its TV special Samurai Warriors: Legend of the Sanada.
Koinuma commented that a rock song would fit the cruelties of war the team wanted to capture in this title. Kiyoharu remarked in Kuroyume's video message for the media event to celebrate the series's tenth anniversary that they agreed to the collaboration to commemorate their anniversaries in unison. At the time of its recording, Reverb was not yet created so he had little to say about it. He did state his wishes for it to completely fit its source material.
Consumers can digitally purchase the single through one of five Samurai Warriors 4 music cards, or cards which have pin numbers for downloading Reverb online. The collaboration product code included on the single and these cards unlocks the "Black Feather" heirloom (one-time use each battle in which user momentarily enters a hyper attack state and gains the Slay element to their attacks) and the option to listen to the image song during battle.
Lyrics
No, don't fade, melting fantasy! I crawl towards your ending
in vain. The dawning world reveals my nightmare
You were the only one who was severed by fate
Rather than mourn for you, I painfully sing your eulogy
All I have was nothing
Still I cry for nothing
Oh I have a heartache
Still I've lasting ache
The fervent period captured in the ice is cut asunder
The blood spilled for it leaves behind empty passion
All I have was nothing
Still I feel that nothing
Should I pray and look above
lucid flower petals would shower around me
My heart is just a mess
I cry out from this insanity
towards the light and darkness, towards the future when I can see you
Filled with that loneliness,
the memories within me
repaints my field of vision, to a strange new aesthetic
Feathers resemble the sword
Touching the rain with both hands,
ever so gently, and with some time, flower petals would blossom before me
My heart is in hysterics
Consumed with madness, I cry out
Is there a future when I can see your light and shadows again?
