Introduce me to the アニメ character with the saddest backstory あなた have ever heard.

Meet Ayano,from Mekakucity Actors.Her mother was killed,her father was possesed,her crush hated her guts,she got terrible grades.And surprise surprise,she suicided.By jumping off a building.
But don't worry,she gets revived in the Correct Route.

Lucy from Elfen Lied. It's messed up

Basically all the characters of Tokyo Ghoul, especially Kaneki Ken. His dad left when he was a kid, his mother died when he was just a kid, he's a loner with only one best friend, then Rize ruins his life, turns him into a ghoul, and etc, etc...

HE DIDN'T DESERVE ANY OF IT!! He only wanted to go on a date. My poor baby cinnamon roll. *cries*

Hakuryuu Ren~ from Magi
I wouldn't say that his backstory is the saddest but it's one of the most tragic ones I've seen

Spoilers from both the アニメ and the manga

He once had a happy life until his evil mother indirectly killed his two older brothers and his father when he was little.

Not to mention that years later he got rejected によって the girl he liked and he got his arm and legs chopped off and now hates the フレンズ he once had >.<

Gaara from the NARUTO -ナルト- series.
The poor kid just wanted to be accepted since he was hated/feared によって his entire village for something that wasn't even his choice. Even his siblings feared him and his own dad tried to kill him numerous times (seriously, screw that guy!). Then something happened one night that made him turn into a psycho [not gonna spoil it, it's better if あなた watch it :'( ]
Good thing is he started to develop from a psycho murderer to a respectable leader as the years passed by! :) That's why I 愛 him~ <333

Haruka Kotoura is a girl who was born with ESP, the ability to read minds. As she has no real understanding of this ability and tends to blurt out everyone's thoughts, she becomes ridiculed によって her classmates and even disowned によって her parents because of this talent, eventually leading her to live alone. Anime- Kotoura-san