The Dark Woods Circus Series (暗い森のサーカス Kurai Mori no Circus) is a series of 5 songs, plus one thought to have relations to the series, composed by Machigerita-P. The songs mainly feature Hatsune Miku, although Kagamine Rin, Kagamine Len, and KAITO make an appearance in the song Dark Woods Circus. This series has a novel adaptation and it was released on July 27.
The songs tell of Miku's insanity, when being shipped to an asylum, she and others are deformed and sent to a circus, where eventually she commits suicide, is sent to hell, and finally spends the rest of eternity as the Grim Reaper.
Note: This song is know as "Steel Cage Princess" in western fandom, but "Steel Queen, Caged Princess" is more suitable. This tradition comes from SakeBliss's mistranslated title.
The first song in the series. The literal translation is Steel Queen, Caged Princess. The song is about Miku being held captive and being put in a "cage" by a "Queen" in a "castle". It is revealed that Miku was actually going insane, and the insanity is locking up her sanity in a "cage". (Note that in the song "Wide Knowledge, Madness" it shows how Miku is sent to an asylum and they start deforming the patients. Though it isn't in the series, it is related.)
暗い森のサーカス / Dark Woods Circus (Kurai Mori no Circus)
The second and most well known song in the series. In this song, Miku and others are now deformed and are in a circus where they are ridiculed by the visitors. Miku is now a "Deformed Diva". Rin and Len have both of their heads on the same body. KAITO is "The One who Likes to Eat Things Cold", hinting at caniballism (Cold Things = human flesh). They all hate the circus, although Rin pretends to like it, while Len and Miku express their hatred openly.
The third song in the series. It reveals that Miku was married and taken away to the circus, then later commits suicide by cutting her arms and legs off, which is represented by the blue ice on her arms.
Note: This song is know as "Red Swamp Bottom" in western fandom, but "On the Bottom of Red Swamp" is more suitable. This tradition comes from SakeBliss's mistranslated title.
The fourth song in the series. After Miku commits suicide, she is sent to hell, which is known as the "Red Swamp". She states that she is in pain, her skin burning to dust, her eyes melted beyond recognition, and her intestines being dragged on the floor. She says that she doesn't want to hear people begging God to let them leave, saying they deserved it for their selfish desires.
In the PV, it shows an insane Miku being interned in a sanatorium where people are deformed. Machigerita-P later stated on his blog that even though the PV was related to the series, the song itself was not a part of the series.