This is Yuni from Katekyo Hitman Reborn. She is Aria's daughter and Luce's grandaughter, she ends up sacrificing her life so then everyone can go back to the past.
The Big yellow/orange thingn in the middle is her life flame.
In one of the latest chapters of this manga she can not be found in the past but then suddenly appers.
Yuni is also spelt Uni.