When studying Japanese... just remember...
This image won't appear for me.
Anyway, about Grenom, I don't know how much you want to know, so here's a quick blurb:
In the lore, she's a Ghoul, similar to those found in Arabic lore but obviously with some differences. She's a djinn who gains power by consuming other lifeforms (more powerful the lifeform, more power gained). This power gives her superhuman strength, agility, potentially eternal youth, and the regenerative abilities you mentioned. Depending on her previous power accumulation, she can recover from various degrees of injuries, ranging from re-growing limbs to fighting off toxins. She is not, however, invincible. Her heart, while it can repair itself from certain injuries, is vulnerable, as it manages her bloostream which contains her healing power. Her head/brain are also sensitive, and ghouls are susceptible to fire (Gren's own phobia).
Anyway, her father is a really, really old mother-fucker who is tired of being hunted over the millinnia and believes that survival is the primary objective of lifeforms, particularly Ghouls (an ancient view carried from his long history and jaded by it). So to keep her safe, he regularly kidnapped humans, djinn and demons and fed them to an ignorant (and young) Gren, whilst simultaneously training her as a warrior and presenting to her existential nihilism.
This continued through her early childhood, but eventually she realized that may be kind of messed-up. But by this time, eating other sentient creatures alive was already a part of her life, and since she can recover from most injuries, she doesn't recognize the fear and severity others face from injury and pain (bear in mind she's been fairly sheltered/isolated from common human society). As such, she becomes something of a sociopath, lacking typical empathy. But, curious little cannibal-thing she is, Gren desperately seeks to understand others, namely her victims, in an attempt to empathize with them. She begins poking into masochism, exploring what pain may mean to them by exploring what it means and how it feels to her. Her attempts are somewhat unsuccessful, however, as she enjoys pain (in a sense) whereas her victims don't like it so much.
Regardless, Gren begins to earn a fascination and admiration for others, especially those "weaker" than her, who her father dismissed as tools or enemies to be consumed for her own advancement. She begins freeing some of her father's captives, helping innocent animals and people whenever she can, and becomes something of a selfless samaritan, but one who tries to sympathize with those she helps rather than empathize.
It's more complicated than that, but that's the basic gist. Does that answer your question from earlier?
edit: PS, she's currently 13, if that matters.