Tsyuchi
On the day that the sky above Aincrad turned from blue to grey, and when the "log out" button disappeared, Ren Shirakawa made the decision to no longer allow anyone else to die on him.
In the real world, Ren sees himself as a weak person who has failed at the things that truly matter. In Sword Art Online, he has chosen to become someone entirely different and fights every battle with a sense of calmness and logical thought and with a steady heart. He does not do it for glory but rather does it for protection.
Initially, his purpose for fighting was to protect Koharu. By having her next to him, he has someone to protect and therefore a purpose in life. Even if he does not understand it yet, having her around helps keep the loneliness at bay.
As they continue their journey through Aincrad, Ren's resolve to protect Koharu helps him gradually open up to other players and provide assistance to more than just Koharu. But while he becomes stronger within this virtual world, he will not release his real self from its confinement and will not acknowledge his past, which he left behind when he entered SAO.
Disclaimer: Majority of the characters appear in this story aren't mine. They belong to Sword Art Online: Integral Factor game.