{{MusicArticle
| titlejp     = 紅い糸
| titlejprom  = Akai ito
| titleen     = Scarlet Thread
| group       = [[bunny rhyTHm]]
| groupCat    = bunny rhyTHm
| released    = 2016-12-03
| convention  = ComiCup 19
| tracks      = 8
| length      = 40:42
| catalogno   = BRTH-001
| genre       = {{Genre|Vocal}}, {{Genre|Instrumental}}, {{Genre|Pop}}, {{Genre|Hip hop}}, {{Genre|Orchestral}}
| website     = 
| digital     = [https://www.bilibili.com/audio/am28769671 Bilibili], [https://www.dizzylab.net/albums/d/BRTH001/ Dizzylab], [https://booth.pm/zh-cn/items/1484423 BOOTH], [https://music.apple.com/album/akaiito/1480639838 iTunes] & [https://play.google.com/store/music/album?id=Bwwhhdr3r6afqgap435trjcfory Google Play]
| image       = BRTH-001.jpg
| banner      = 
| banner_res  = 
| caption     = Portrayed: [[Sakuya Izayoi]] & [[Remilia Scarlet]]
| arranger    = S9ryne
| lyricist    = {{鬼千鶴}}
: {{叁生}}
| vocalist    = {{纓纓EI‎}}
: {{琉芸Miruku}}
: {{小洋}}
| producer    = 
| illustrator = Usagi [https://www.pixiv.net/en/users/3605922 Pixiv]
| designer    = START SEED
| masterer    = {{小洋}}
: CuTTleFiSh
| other_staff = 
; Rap & Guitar
: {{小洋}}

| description = It features vocal and instrumental arrangements of themes from ''[[Embodiment of Scarlet Devil]]''.
| tracklist   =

* {{Track|01|{{lang|ja|紅い糸}}|04:34|lyrics=Lyrics: 紅い糸 (bunny rhyTHm)}}
** ''Scarlet Thread''
** arrangement: S9ryne
** lyrics: {{千鶴}}
** vocals: {{纓纓EI‎}}
** original title: {{lang|ja|亡き王女の為のセプテット}}
** original title: {{lang|ja|ツェペシュの幼き末裔}}
** source: {{EoSD}}

* {{Track|02|{{lang|ja|黑いバラ}}|05:34|lyrics=Lyrics: 黑いバラ}}
** ''Black Rose''
** arrangement: S9ryne
** lyrics: {{鬼千鶴}} & {{叁生}}
** vocals: {{琉芸Miruku}}, {{纓纓EI‎}} & {{小洋}}
** original title: {{lang|ja|月時計　～ ルナ・ダイアル}}
** original title: {{lang|ja|メイドと血の懐中時計}}
** source: {{EoSD}}

* {{Track|03|{{lang|ja|残り香～}}Remained Fragrance|05:00|lyrics=Lyrics: 残り香～Remained Fragrance}}
** ''Lingering Scent ~ Remained Fragrance''
** arrangement: S9ryne
** lyrics: {{鬼千鶴}}
** vocals: {{琉芸Miruku}}
** original title: {{lang|ja|ラクトガール　～ 少女密室}}
** original title: {{lang|ja|ヴワル魔法図書館}}
** original title: {{lang|ja|魔法少女達の百年祭}}
** original title: U.N.{{lang|ja|オーエンは彼女なのか}}?
** original title: {{lang|ja|紅楼　～}} Eastern Dream...
** source: {{EoSD}}

* {{Track|04|dreaming rhyTHm|05:13|lyrics=Lyrics: dreaming rhyTHm}}
** arrangement: S9ryne
** lyrics: {{鬼千鶴}} & {{叁生}}
** vocals: {{纓纓EI‎}} & {{小洋}}
** original title: {{lang|ja|上海紅茶館　～}} Chinese Tea
** source: {{EoSD}}

* {{Track|05|{{lang|ja|紅い糸}} - Instrumental|04:34}}
** ''Scarlet Thread - Instrumental''
** arrangement: S9ryne
** original title: {{lang|ja|亡き王女の為のセプテット}}
** original title: {{lang|ja|ツェペシュの幼き末裔}}
** source: {{EoSD}}

* {{Track|06|{{lang|ja|黑いバラ}} - Instrumental|05:34}}
** ''Black Rose - Instrumental''
** arrangement: S9ryne
** original title: {{lang|ja|月時計　～ ルナ・ダイアル}}
** original title: {{lang|ja|メイドと血の懐中時計}}
** source: {{EoSD}}

* {{Track|07|{{lang|ja|残り香～}}Remained Fragrance - Instrumental|05:00}}
** ''Lingering Scent ~ Remained Fragrance - Instrumental''
** arrangement: S9ryne
** original title: {{lang|ja|ラクトガール　～ 少女密室}}
** original title: {{lang|ja|ヴワル魔法図書館}}
** original title: {{lang|ja|魔法少女達の百年祭}}
** original title: U.N.{{lang|ja|オーエンは彼女なのか}}?
** original title: {{lang|ja|紅楼　～}} Eastern Dream...
** source: {{EoSD}}

* {{Track|08|dreaming rhyTHm - Instrumental|05:13}}
** arrangement: S9ryne
** original title: {{lang|ja|上海紅茶館　～}} Chinese Tea
** source: {{EoSD}}

}}