Marinca is small girl who wears a cloak, a round hat and wields a staff that is almost as tall as her. She has golden, curly hair which covers her eyes, a milky-white skin and pale yellow fairy wings. The words "GAME MASTER", written in shining letters, hovers over her cursor.
Marinca is a person who lets her curiosity get the best of her. For example, she dived in during maintenance to monitor the situation up close and then activated an unused feature to play around with it while the server was shut down. Marinca is also careless, as she forgets to turn off whatever she had turned on, including television, lights, air conditioners and game features. Marinca also has problems finding the right phrase for the situation and she has difficulty in handling a crisis, as she tends to whimper and is at a loss on what to do in such a situation.
Marinca began working at Ymir at around the middle of December, 2025. During the maintenance of ALfheim Online on the December 27, 2025, she dived in from a specialised VR console to monitor the situation up close. During her observations, she discovered many unused functions and models in the quest interface and decided to play around with them while the server was shut down and ended up activating the "Speed up mission" setting. However, as nothing happened after she turned the setting on, she continued monitoring the maintenance, but forgot to turn the setting off before the server was rebooted. Thus The Holy Sword of the Ice Palace quest was accelerated.
After the maintenance, Marinca fell asleep in the office and was woken up in the afternoon, when The Holy Sword of the Ice Palace quest was failed and this caused Thrym to invade Alfheim with Thrymheim and destroy Alne in the process. Because of this unforeseen event, Marinca was ordered to log into the game to investigate the situation. There, she encountered Kirito's party and overheard Yui's report that the items the players lost due to the invasion were converted into scrolls, which could be converted back into items at a bank. Marinca approached the party to confirm whether this was true and explained why was the event triggered and left unchecked and also explained that the Cardinal System had made a backup just after the quest was failed.
After figuring out that Thrym planned to assault the World Tree and New Aincrad, the party wondered how was the event supposed to continue, as they were not lead to a follow up quest. Marinca then checked the Cardinal System's quest generation status and announced that a follow-up event was scheduled for 15:00. After Kirito asked her if there was anything that Ymir could do, Marinca told them that she received a message from her superiors, telling her that there were two options: either they rollback the server to its status two weeks ago, or the new quest must be completed and thus she must join a player party to help clear the quest. She thus asked Kirito's party to allow her to join them, as she could ignore the party size limit due to her status as a GM.
As Marinca is a GM, her name can be seen by any player, even if they had only just met her, while usually, players who have met for the first time cannot see each others name over the other party's cursor.