Based on the Vocaloid Song "Yubikiri" by Scop: www.youtube.com/watch?v=TnTPc8…
Yes, the girl on the right is Hatsune Miku. (•ω•)
There are two main symbols in this drawing. The first one is Yubikiri and the second one is The Red String of fate.Yubikiri
Yubikiri (指切り) means "finger cut-off". It is the original Japan version of the modern "pinky promise". In this version, when one breaks the promise, they have to cut off their pinky. In the past, Japanese prostitutes were known for cutting off they pinkies as a sign of their love for their partner.
There are two sides of the drawing. I would name the left side "Yandere" (meaning lovesick) and the right side "Prostitute" (because that's what the right side of the drawing portrays).
The Yandere is shown doing the Yubikiri as a proof of her love to an unseen partner, as seen with the cut on her pinky. The Prostitute is a representing the Yandere's inner thoughts on how she is cutting off her finger to show her love like how prostitutes do.
(I think I just explained my interpretation on the song above too xD)The Red String of Fate
The Red String of Fate is an invisible red string that is believed to be tied around the pinkies of two destined lovers. The string can be stretched and tangled, but it can never be broken.
In this picture, the blood from the Yandere's cut forms a shape that is somewhat similar to the red string, again, another symbolism of her intense love. The translucent "string" coming down from the cut is just a symbol of the Red String of Fate, to balance out with the real red string on the Prostitute's pinky.
It's been one month since I drew something. Sorry about that! I got busy, but hopefully I can get back to drawing more again! (｀・ω・´)