Sigma Klim

Sigma Klim also know as Zero Sr. started out as the main antagonist later turns out to be both the main  protagonist/antihero in Zero Escape: Virtue's Last Reward it turns out that Dio is the true main antagonist of the game. he is 22 both 22 and 67 years old douring the game.

On December 31, 2028, Sigma lost both his arms (which were replaced by mechanical prosthetics), and his right eye in trying to "save a woman" from the where  was first reported, when investigating it with.

After the mission, which ultimately failed, causing Radical-6 to spread across the world, Sigma went to the Moon and spent the next 45 years working on the AB Project, which would be the key to stopping the spread of the disease with the help of the consciousness of his younger self.

During those 45 years, Sigma would meet, who would help him with the project, and become part of. He would also create the, including , who would participate in the AB project, as well as giving birth to his clone and "spare", , and would create the AI , along with the bracelets and chromatic doors, as well as asking Tenmyouji and Quark to come to.

After fully developing the AB Project, Sigma's consciousness switched places with that of his 22-year old self. While the younger Sigma participated in the Nonary Game in 2074, the older Sigma would infiltrate the trap-infested facility where Radical-6 was first noticed in 2028 with the help of Phi, where he would lose his arms and eye. Four months later, in April 2029, his consciousness would switch back with his younger self's, who had reached the end of the game, where his younger self would begin research on the project, thus completing the cycle.

in Tenmyouji end

Sigma finds a hologram of Zero Sr. in the while searching for Tenmyouji and Quark prior to the third round of the AB game.

In his message to Sigma, Zero Sr. mentions termites, how a termite mound is similar to a rhizome, and likens humanity to termites. He says that mankind might be building something in unison they are not aware of and can only be appreciated by the intelligence of a higher order. Every human is an "oblivious cog in a tremendous machine programmed by millions of years of human DNA." The concept is that the termites all do their work, fill their niche, and mind their own business. Their activities by themselves are mundane. However, when humans look on a termite mound, they see a wonder, a work of art that is a product of the collective efforts of the termites. If one could look at human activities from a more all-seeing vantage point, perhaps the activities of humans would be equally magnificent.

He then gives Sigma the password for Bomb 1 (BQZ RGJ DXR). He asks Sigma if he is aware of his time jumping abilities and warns him not to tell anyone about their meeting. Before the message ends, Zero Sr. says that he looks forward to speaking with him in person. It is revealed that Tenmyouji and Quark saw the hologram, which leads them to betray Sigma.

in Phi END and Another Time END
Before "Kyle" wakes up, Zero Sr. instructs Phi that she can answer any questions about the test site to anyone besides "Kyle". He also carries "Kyle" to the where he and  are looked after by Luna. After he wakes up, sees a hologram of Zero Sr. after speaking with Phi. He states that he cannot answer any questions about the to ? because if he did, the timeline where the virus was contained would disappear.

his main goal as zero Sr is to go back in time by any means and stop Radical-6 with is a lethal airborne virus unleashed by Free the Soul witch killed 90% of all life

when sigma goes by the name sigma he is a lot differen