Who is the main character in the 'one leaves game story'?
In the 'one leaves game story', the main character could be anyone. It might be a warrior who has fought many battles in the game and now, after achieving victory or facing defeat, decides to leave. It could be a mage who has mastered all the spells in the game world and chooses to depart in search of greater magic. Or perhaps it's a thief who has stolen enough treasures and now wants to retire from the game's underworld. Without more information about the story, it's impossible to be certain about the identity of the main character.
There's no way to tell for sure who the main character of the 'one leaves game story' is without more details. However, it could be an adventurer who has completed all the quests in a game and is ready to move on. Maybe it's a character who has had a conflict with other in - game characters and decides to leave as a result. It could also be a simple avatar representing a player who has made the decision to leave the game, in which case the main character would be whoever controls that avatar.
Since I don't know the specific 'one leaves game story', it's hard to say who the main character is. It could be a protagonist who has been on a long journey in the game world and is now leaving for some reason.