It is a novel series written by Nahoko Uehashi and published between 2006 and 2009. Later, the production studio Production I.G adapted it into a 50-episode anime series in 2009. Its genres are drama, fantasy, and memoirs. The score was composed by Takayuki Hamana, and finally, the character designs were done by Takayuki Goto, who has worked on many of Production I.G's works and designed the characters for Hunter x Hunter (1999).

How do I view this anime?

The main character, Erin, is a name for innocence and joy; Erin is a name for compassion; Erin is a child. Born with green hair and green eyes in a vast world full of life and creatures, she came with an unparalleled affection. An affection for creatures greater than her in size and strength, an affection for the endless colors and shapes of plants, an affection for everything that is alive and breathes. The days and years pass, and her passion grows and rises to bring change to a vast world filled with the greed and malevolent intentions of those who valued their interests over that beautiful, living world. Her title is the "love of life."

Is it like a children's story?

The truth is that the novel was originally aimed at children, and so is the anime. Anyone who has watched the anime will notice things that confirm it is directed at children, or at least a child's way of thinking. This includes the dense repetition of characters' memories and thoughts, as if to say in a child's language, "My goodness, don't you forget anything," in addition to explaining every single detail of the feelings and emotions presented in the anime. This aspect might become tedious for an adult viewer. But are the ideas presented simple and passive, ones that adults cannot interact with? The answer is: No!

It resembles "Beauty and the Beast."

The essence of this story, and what drives its events, is Erin's relationship with Lilan, one of the creatures known as the "Beasts of Prey" (Toudas), which are giant predatory creatures. This relationship is truly an example to be followed in writing about friendship between a human and a beast. What makes this relationship unique is that it wasn't created by a power or a medium that made it easy for Erin to communicate with and understand these so-called beasts. Instead, it emerged through a long series of joys, sorrows, and catastrophic experiences that strengthened the bond between them. But despite all that, it remains a relationship between a human and a monster! No matter how hard they try, there is a barrier between them that cannot be broken, and crossing it could lead to disaster. By this barrier, I mean the instinct upon which this beast is built.

In the end, this anime is a lengthy production that you can be patient with and derive great pleasure from. You will enjoy the events of a green-haired girl, her stances, and her confrontations with life, childhood, friendship, love, and loss.