SKi Unit-4

 is the twentieth album released by Seifuku Koujo Iinkai, and their fourth subunit compilation.

Tracklist

 * 1) Erimaki to Kage Blues! (えりマキと影ブルーっす！)
 * 2) Raku Janai no yo! (楽じゃないのよ！; It's not easy!)
 * 3) Tottemo Ippai (とってもいっぱい; So many)
 * 4) Watashitachi wa Erimaki to Kage no Nisemono Janai (私たちはえりマキと影の偽物じゃない; We are not Erimaki and Kage imposters)
 * 5) Hot Chocolate (ホットチョコレート)
 * 6) Usagi-san no Koi Monogatari (うさぎさんの恋物語; Rabbit's love story)
 * 7) Time Machine (タイムマシーン)
 * 8) Take me to your heart
 * 9) Chisei no Shiesuta (知性のシエスタ; Siesta of the intellect)

Featured Members

 * Hashimoto Mika (Vocals: #8 Chorus: #2 #5 #7 #8 #9)
 * Miura Eriko (Vocals: #1 #2 #3 #5 #6 #9 Chorus: #1 #2 #3 #6 #9)
 * Akiyama Ayaka (Vocals: #7 #8 Chorus: #8)
 * Endo Maika (Vocals: #1 #2 #8 #9 Chorus: #1 #2 #3 #6 #8 #9)
 * Nishibori Mako (Vocals: #1 #2 #3 #8 Chorus: #1 #2 #3 #6 #7 #8)
 * Koga Miyuki