God I should probably explain myself since I won't be making a sequel to this since everyone is dead.

I never thought about who was sending Rin the files but since she was only killing Vocaloids it could be Utauloids.

also the people sending Rin the stuff wanted to toy with her and make her insane, no real reason behind it, that's just what they do.

there wasn't much description on Rin's feelings because she was slowly losing her mind and she didn't know what to think and the only thing she wanted to do was kill.

so yeah I hope this gives my 2 curious guest's some closure.

~TheUltimateShipper27