Rira in the Novel
Rira has short, lavender colored hair which usually hand in her face and don't even reach to her chin. She has blue eyes and is usually illustrated in Hosea Academy's school uniform.
Rira, being a part of Haruhiko, represents his side which wants to survive, find love and breed. Much like Ruru in the Anime, Rira doesn't know she's a part of him and tends to make sexual jokes or ask him for nude portraits of him.
The enemy of Volume 2 wanted to challenge Haruhiko and created a world where he didn't defeat Ruupa and 2/3 of humanity did die. To let him suffer even more, he seperated his soul in two people. In Haruhiko and Rira. However, none of them know about that.
Rira's ability is called "Undead Daughter" with which she is virtually immortal and can heal other people within a short time frame of their injury.