Name: Seiya Senji The older brother of Toya Senji and the goal Toya strives to surpass. A genuine prodigy who achieved results in every field imaginable—academics, martial arts, and the arts—he was a talented individual who built a fortune at a young age and had a promising future. His overwhelming talent and achievements, combined with constant comparison by relatives, made him the very embodiment of Toya's inferiority complex. His true identity is a Returner of the universal genius Leonardo da Vinci, and he was a maverick who actively engaged with the secular world despite being a Returner. He was also one of the founders of the "Forest of Greats," the very person who established the organization alongside Neumann, Xiang Yu, Ein, and Picasso, and he was the leader who guided the Forest. Unlike Toya, who has black hair and eyes, Seiya has an appearance that deviates from typical Japanese features, with blonde hair and violet-blue eyes. In fact, Seiya is an adoptee of the Senji family, which explains the stark difference in their looks. Seiya's personality is gentle and sincere. He is a thorough pacifist and dislikes useless conflict. Treating everyone with a polite tone and possessing boundless kindness, he is admired by many, both humans and Returners alike; Xiang Yu was convinced that Seiya was the one meant to lead them all. However, his overly kind nature is also a fatal weakness for a leader, as he cannot fully discard his emotions. Notably, he has a severe brother complex. His entire code of conduct centers on Toya's existence, and he feels his reason for being is to "protect his brother and show him the way." However, he feels a sense of guilt toward his brother, who works desperately to equal him, viewing the abilities gained through Da Vinci's talent as "cheating" and striving to leave achievements through his own effort to face his brother properly. This affection for his brother, if flipped, is so excessive that he would destroy the world to stop anyone who hurts him—a trait that, combined with his aforementioned weakness, leads to disaster. Talent: "Universal Vessel." A talent derived from his past life as Da Vinci, the man hailed as the universal genius. It is one of the strongest abilities in the series, allowing him to acquire talent in any field by studying under others. While it is a late-bloomer type ability, he can theoretically use any ability that appears in the series, overturning the very concept of a Returner's talent.

The Returner of John von Neumann, the mathematician who became the father of the modern computer. She is the coordinator of the "Forest of Greats" and one of its founding members. She is the de facto leader in charge of the command system for her comrades, and as such, she has the members carry mobile terminals to receive her instructions. While her age is stated to be 19, she does not look it at all due to her persona and appearance described below. Her appearance is that of a young girl always seated in a wheelchair. She is characterized by grey hair reaching her waist, devil-like horns and a monitor on her head, and pupils that form the shapes of '0' and '1'. These are based on the anecdotes of being the father of binary computers and being called a devil in life due to her incredible calculating power. However, contrary to her lovely and petite appearance, she hates the words "cute" or "small," and these are considered taboo among her companions. Her personality favors rational thinking befitting a mathematician, and she dislikes uncertain things like fortune-telling or prophecies. Her way of speaking is monotone, giving a somewhat cold-blooded impression, but she also has a cute side, such as holding a grudge for three days if her calculations are mocked as mere prophecy. Talent: "Lord of the Cyberworld." A talent that places computers worldwide under her control. No matter the computer, hacker, or programmer, the moment she exercises her talent, everything is hacked and hijacked, making it a near-invincible ability in modern society where everything is exposed to her. However, it is not a perfect talent and has one major flaw: its influence can be avoided in "out of service" areas where radio waves do not reach.

The Returner of Xiang Yu, the Hegemon-King of Western Chu, who was both a general of Chu and a king of massacres. On the other hand, he is one of the founding members of the Forest of Greats and is close acquaintances with Neumann, Ein, and Picasso. His appearance is that of a young man with grey hair, characterized by black double pupils. He treats others frankly, regardless of whether they are friend or foe. Talent: "All-Encompassing Instrument." A talent that allows him to freely manipulate objects covered in the black mist emanating from himself as weapons. The activation condition is to wound himself or another; even a small scratch is sufficient for this "wound."

The Returner of Albert Einstein, the German physicist who published the "Theory of Relativity." A Returner belonging to the Forest of Greats, she is responsible for combat and large-scale transport due to her talent. Like Neumann and Picasso, she is one of the founding members. She has short bangs that don't reach her eyebrows and long hair down to her back. She wears a pantsuit but is a major misanthrope (hating men), with a sharp edge toward males in every word she speaks. Talent: "Spatial Displacement." She can perform instantaneous movement by swapping spaces in less than a second. Because she swaps spaces, if an object spans the boundary of the swap range, that object will be severed between the inside and outside of the range. This applies to human bodies as well. Her weakness is that she can only teleport to coordinates she has registered by visiting them on foot.

A Returner belonging to the Forest of Greats, whose past life was the world-famous painter Pablo Picasso. His position in the organization is unclear; he is a non-combatant who basically stays at the base continuing to paint and does not usually stand on the front lines. One of the founding members who started the organization along with Neumann, Seiya, Xiang Yu, and Einstein. A petite Returner wearing white clothes stained with numerous paint marks, his height is about the same as a child's. True to his appearance, he is as bright as a child, innocently describing the bickering Neumann and Xiang Yu as "getting along!" or painting all over Xiang Yu's base; he has the personality of an innocent child.