I finally have figured out the name for a manga I read 7 years ago and for those who love twilight, you might actually love this manga series as it's quite oddly similar to twilight just more friendship based and less romantic/sexual tension.
A synopsis of this is there's this girl, I don't remember her name too good, who has a heart condition and is said to not ever make it past age 15 who meets this vampire dude named Toya who has to find a human partner to live with who will share her blood with him and live alongside him. The girl offers her blood because she wants to live longer but Toya says "ew no" because he dislikes the sight and smell of blood. He also thinks humans are weaklings but forms a friendship with the girl and helps protect her everytime something happens in relation to her heart condition and they both ultimately start seeing the world differently.
I 100% highly recommend this to anyone, but especially those who love twilight (weirdly enough too, these came out around the same time, this manga series from 2001 to 2013 and twilight from 2005 to 2008).
by Remi-pr