Heartbeat Clocktower

Heartbeat Clocktower was not the first of these songs to be released; it was released April 25, 2010, long after many of the songs had been released. However, it serves as an overarching theme for all of the songs, as well as establishing a background. It is the fourth song in the Clockwork Lullaby series.

The official English title of the song is "Clockwork Lullaby 4".

Plot
The song concerns a mysterious clocktower and its actual guardian, GEAR. The dead owner, embodiment of Greed and former guardian of the clocktower, the "Collector", created a theater for the "Collectibles" where they forever enact their story.

GEAR's main concern is to keep a young girl "with ugly burns on her body" (The Clockworker's Doll) alive through the clocktower, and if it stops, she will die.

Performing his task day by day, he describes other inhabitants of the clocktower, including the Master of the Graveyard, who devours any helpless visitor who had the bad luck to end up in the theater, and a "pretentious" servant girl (Waiter) who "indulges in selfishness", but expresses sadness for the loss of her "other half" (Irregular).

He also observes how the Kayo's Scissors and the Venom Sword continue to be "dormant". GEAR, realizing that the clock was going to stop soon, sacrificed himself to keep it running by taking out his own heart and using it to power the clocktower.

Singing Roles
KAITO as GEAR

Non-Singing Roles
Miku Hatsune as Clockworker's Doll

MEIKO as Master of the Graveyard

Rin Kagamine as Waiter

Miniature Garden Girl (EC 983)
Miniature Garden Girl occurs 7 years before the events of Heartbeat Clocktower. The song details the life of the Clockworker's Doll before the incident in which she is severely burnt.

Master of the Court (EC ???)
Although Master of the Court hasn't a specified year, it can be inferred that it occurs after Heartbeat Clocktower and before Capriccio Farce. Because of GEAR's sacrifice, the Clockworker's Doll received the power of the Marlon Spoon, restoring her condition and transforming her into the Master of the Court, who continues the legacy of her father, seeking the Seven Deadly Sins.

Curiosities

 * The colored gears at the beginning of the song reflects how the Deadly Sins arrived at the theater. The first four gears that appears correspond to the Vessels of Sin collected by Gallerian Marlon, joined shortly afterwards by the two gears that match for Envy and Lust. Finally, after the gears join to the logo in the right side of the screen, the green gear representing Wrath falls on the left side, avoiding the logo. This reflects how the last Sin is still missing.
 * Other than the first time the gears all appear, the teal gear (that corresponds to Sloth) spins at a slower speed than the other gears, which all spin at the same speed.
 * This song was re-arranged by Mothy to promote the Daughter of Evil -Prefazio of Blue- novel and ending up being its theme song, under the name of "針音ノ時計塔 -handbeat clocktower-" (Sound of Clocktower Needle -handbeat clocktower-), a track from the "Daughter of Evil -novel series-" campaign disc.