Relations. Sister × Sister. Soundtrack CD
| Composed by | Heaven's line / TremoloVibration |
| Published by | TwinTail MUSIC |
| Catalog number | AL-10002 |
| Release type | Game Soundtrack - Official Release |
| Format | 2 CD - 25 tracks |
| Release date | April 28, 2011 |
| Genres |
| 1 | LOVE HEART |  | |
| 2 | warmth | | |
| 3 | DEAR | |
CD 2
| 1 | LOVE HEART (one piece) | | |
| 2 | Adored Girl | | |
| 3 | Princess Girl | | |
| 4 | Childhood Friend Girl | | |
| 5 | Genius Girl | | |
| 6 | Elegant Girl | | |
| 7 | 優しいお姉さん | ||
| 8 | 気持ちのいい朝 | | |
| 9 | 楽しい日々 | ||
| 10 | 退屈な日常 | | |
| 11 | たまにはこんな日も | ||
| 12 | お洒落にデート | ||
| 13 | ハプニング！ | | |
| 14 | 夕焼けの街 | | |
| 15 | お疲れ様 | ||
| 16 | Blauへようこそ！ | ||
| 17 | お忙しいですか？ | ||
| 18 | 焦燥感 | ||
| 19 | ひび割れた硝子 | ||
| 20 | 古いレコード | | |
| 21 | つのる想い | ||
| 22 | 想い重ねて |
