Volunteer Spirit

 is a compilation box set released by Seifuku Koujo Iinkai, commemorating their twentieth anniversary. It is officially credited as SKi's 36th, 37th and 38th albums, collectively.

The box set consists of three CDs and one DVD.

CD 1: Kiyokuta Dashikuutsu Kushiku

 * 1) Prolouge (Josho) (プロローグ（序章）)
 * 2) Volunteer Spirit
 * 3) Kuroi Hitomi(Re-Recording)
 * 4) Ai to Yuki no Omoiyari
 * 5) Sayonara wa Deai no Ashita he no Shirushi
 * 6) Meguriai
 * 7) Emerald no Densetsu
 * 8) Jidai wa Circus no Zou ni Notte
 * 9) Kurukuru Handkerchief
 * 10) Namo Nakigoe ni
 * 11) Itsumo no Youni
 * 12) Kiyokuta Dashikuutsu Kushiku
 * 13) Chikyuu ni Ai wo
 * 14) Epilogue (Shuushou) (エピローグ（終章）)

CD 2: Ai to Yuki no Omoiyari

 * 1) Dokyusei
 * 2) Utakata no Yume
 * 3) LOVE×2
 * 4) Usagi-san no Koi Monogatari
 * 5) Nagai yo
 * 6) Kawattenai Wakattenai
 * 7) Seitansai no Uta
 * 8) SKi no Theme
 * 9) Deai
 * 10) Obaachan ga Suki
 * 11) Kimi to Kyuukyuusha
 * 12) SKi no Hashire! Eight Monday (SKiの走れ！エイトマンデー; SKi Runs! Eight Monday)
 * 13) Koi Seishun Shoujo
 * 14) Illumination
 * 15) Sono hi ga Kuru Made

CD 3: The longest female group idol "20th Anniversary Festival"

 * 1) Yonimo Tushigi na Tsuru to Kame to no Monogatari" Tsuru Kame Kotobuki" (Kotobuki Tai)
 * 2) Hatoyo-sha e Nigasa wo (Kotobuki Tai)
 * 3) Hagaitai! (Kotobuki Tai)
 * 4) Otona wa Wakatte Kurenai (4-Nin 1-Kumi)
 * 5) Sotsugyou (4-Nin 1-Kumi)
 * 6) HELP no Kisetsu (Hellow)
 * 7) Good-Bye (Hellow)
 * 8) Hikkoshi (BPG)
 * 9) ANGEL DREAM (Okuwa Anna)
 * 10) Mikazuki (みかづき; Crescent moon) (Hashimoto Mika)
 * 11) Slow Ballad no Youna Koi (スローバラードのような恋; Love like a slow ballad) (Hashimoto Mika)
 * 12) Maraca (THE DUET)
 * 13) GAME (THE DUET)
 * 14) Kako ni Oite Iku Mono Mirai e Todokeru Mono (過去に置いていくモノ・未来へ届けるもの; What we leave behind in the past and what we deliver to the future) (Hashimoto Mika)