"Streaming Heart" is featured in the album Conti New, which was released March 26, 2014. Additionally, this song has made it into the Hall of Legend, reaching over a million views.
The lyrics of this song are unusually vague, so that even the perspective of the singer is ambiguous. In both cases, the song is about the ending of an abusive relationship. Both the man and the woman in the relationship know that it isn't working out, but the girl is passive and is afraid to speak up, while the guy is too full of pride to drop things.
The first interpretation is from the perspective of the man. He begins to see another girl(Miku) while still in his relationship. The second interpretation says that Miku is representing the heart of the girl, and the song is also sung from that perspective. Her heart is pushing the girl to leave the relationship, but she can't quite do it. The heart manipulates the girl into finally resolving to end the relationship. Even when the boy tries to keep her, she manages to get him out of her life.
vocaloid.fandom.com

Stealth - music box ver., thanks to R3 Music Box
Assault - original ver.

In-Game preview? Do you actually need that medic bag so bad?
Fine, here it is:

Like always, it's a .pdmod file, who use it nowadays, lol
it's Custom OST format, so download it first!
You know how to install them, right?    (No? You wanker...)