"[2][3] Ringo Sheena had taken an interest in the band in the early 2000s, attending live concerts of theirs before their debut in 2003.

"Koroshiya Kiki Ippatsu" was a single released to commemorate Soil & "Pimp" Sessions' 10th anniversary.

[6] A bonus track on Circles, "Koroshiya Kiki Ippatsu (Death Jazz Ver.

Sheena made a guest appearance, performing "Koroshiya Kiki Ippatsu" and her previous collaborations with the band, "My Foolish Heart" and "Karisome Otome."

[6] It features the members of Soil & "Pimp" Sessions as assassins on a luxury liner, and Sheena as a woman manipulating them.