And after you're done crying, listen to the Nico Nico Chorus Classical version.
You think Servant of Evil is sad? Try the Classical version.The Kagamine twins seem to be the masters of this, with songs like the aforementioned "Kokoro", the follow-up, "Kokoro/Kiseki", and things like "Servant of Evil", "Recycle Bin" and the sequel, "Salvage".The Thief and The Guardsman The sequel sheds some light on the Mercenary, who saved the girls, and what became of them.While it has a happy tune and even a happy ending, it's just heartbreaking to see their lives as experiments. The Guinea Pigs and The Mercenary Gumi and her friends are the guinea pigs of a group of scientists.Another tipoff about this song? 1, the first few pictures are Rin burnt at the stake, 2, it's based off The Little Match Girl. Mothy also wrote moonlit bear, Miniature Garden Girl, The Daughter of Evil Series, and Desert Bluebird.
Most if not all of Okame-P's songs are known for being REALLY sad, but none more than "you're not alone".