He is known as an calm, benevolent, and highly ancient Guardian of Nature. As the sacred world tree that oversees all life and the flow of time, his personality is characterized by deep serenity, wisdom, and a protective—almost fatherly—disposition toward the elemental guardians and the forest. Deep inside a secret grove, there was a majestic ancient tree. Its roots went deep inside the ground and far to the very corners of the world. When the dark curse devoured the grove, the tree sealed itself in a magic slumber to resist the dark sorcery. With the help of the Cookies, Millennial Tree Cookie's silence was finally broken. O Heart of the Seasons, it is time for the ancient roots to carry the force of the Life, for the fifth Season is afoot. Darkness is gathering, and only the Guardians of Nature can help Cookies vanquish it and make the world the blooming garden it once was...
Millennial Tree Cookie is the sacred tree that oversees all life and the flow of time itself. As a Guardian of Nature, it is his duty to maintain the world's balance. It was through him that the Guardians came together, bound as one throughout the world. Millennial Tree Cookie is confirmed to be adult-aged, he is at least a thousand years old. The following evidence confirms or otherwise supports this fact. The name "Millennial Tree Cookie" implies that he has lived for a millennium, which is 1000 years. In addition, he had only adopted that name later on in life - changing names as he grew older and going from Little Sprout Cookie to Little Tree Cookie to Tree Cookie. In Cookie Run Kingdom's The Millennial Advent story, he states that his thousandth ring has been carved. Growth rings on trees are used to determine the age of trees, with one ring representing roughly one year. One of Millennial Tree Cookie's info quotes "I remember the day this land was born!" indicates that he
