Rurushi Ru

Rurushi Ru (ルールーシー＝ルー), also known as the Vampire Princess, is a Vampire and the first wife of Hiraku Machio. She appears to be a "Daywalker" type vampire, allowing her to be active during the day like normal humans.

History
Se used to live in the castle of the Kingdom of Galbart, before it was occupied by humans. Since then she has lived in various kingdoms, either continuing her research or attending to the requests of noble families, which gave her fame and reputation throughout the world. After an incident with some nobles in the Kingdom of Golsen, she decided to run away from there, since they put a bounty on her.

Having eluded her pursuers, she entered the Forest of Death, where she would eventually encounter a group of Inferno Wolves. Wanting to test his strength, she confronted them but was easily defeated. The wolves' master, named Hiraku, stops the attack, happy to see another "human". Desperate for energy, she bites into him and her vitality returns. However, seeing this as an attack, the wolves attack her once more until Hiraku stops them again. He allows her to drain some blood to restore her strength and takes her to see his farm.

Ru is amazed by Hiraku's crops, which are new to this world, and explains that she is a medical researcher. They become friends and Hiraku asks Ru to move in with him. Ru agrees and they become a married couple. Hiraku adds a herb garden to her fields to help Ru's research.

Abilities
Like all vampires, she drinks blood to revive her vitality and magic strength. When her energies are low, she can reduce her size/age to conserve energy. Her magic allows her to create shields/barriers and project illusion of magic clothes. She also notes she does not use her magical abilities in combat due to it tiring her out and reducing "firepower" in physical battle.

Aside from being a famous mage and well-known pharmacist, Ru is also a celebrity in making magical tools. She has a keen mind, is knowledgeable about politics of her region of the world near and around the Forest of Death.

Tia
She once belonged to a kingdom and was frenemy with Angel Tia. However, "trouble" accrued in the Kingdom, in which these events forced her to flee the Kingdom.

HIrako Machio
Ru is Hiraku's first wife and the one to birth his first child, She loves her husband and is always kind and supportive, she tells him to take breaks and not overwork himself, Ru met Hiraku when the Kuro's pack attacked her in self-defense, Hiraku called them off and Ru bit him and drank his blood to heal herself, this resulted in the inferno wolves attacking her again as she did just bite their master, Hiraku told her that it didn't hurt and allowed her to drink his blood again. After she was healed from her injuries, Hiraku showed her around his home, and later that evening Hiraku asked her to marry him as he was so lonely and wanted company, Ru accepted and an over happy Hiraku jumped on her and it was implied that they slept together,

Even though Ru loves her husband she had trouble handling his restless nights of passion so she recruited other girls to help lighten the burden. She also used her magic to make herself look more childlike to ensure Hiraku controlled himself around her but would take her true form when she was willing to sleep with her husband.

Alfred
Ru is the mother of Alfred. She loves her son and happily dotes on him along with her husband,

Ann
Ann serves Ru as her maid, However Ann cannot tolerate her sloppy lifestyle and during the tournament, when fighting Ru, she snapped and told her about how she hates that she never puts anything back and how her room is such a mess. Ann was the one who helped Ru deliver Alfred.

Sena
Sena and Ru get along well. In the anime When Ru went into labor Hiraku was too scared to stay with her so Sena volunteered to stay with Ru and hold her hand during the delivery preformed by Ann.

Flora
Ru is Flora's cousin and they get along. Ru is happy to let Flora spend a night with her husband too and is supportive

Lupumirina
Lupumirina is Ru and Hiraku's second child, as her Mother she loves and nurtures her.

Trivia

 * Ru has been noted as "the Vampire Princess" on manga chapter 127. This hasn't clarified if she really is royalty.
 * Though she never had a ceremony with Hiraku, they consider themselves married.
 * In the anime near the end of episode 10, it's indicated that she is pregnant with Hiraku's child. In the manga, Ru becomes pregnant in chapter 25.