Naoki Mayaba does not belong in his reality. In school he has very few friends, and does not fit in. His parents argue, sometimes violently. They talk about splitting. His sister, Mai, struggles with life itself. Everything is falling apart.
Naoki's only escape from the cruelty of life is a VRMMORPG game he discovered, ALfheim Online. His goal is to find his identity inside the game in order to become stronger and more able in real life.
No one has gotten past Floor 75, even in the original Aincrad. In New Aincrad, the top Floor reached is currently 28. Reaching the top may be tough, but it could give Naoki his identity.
Facing many challenges from both realities, including guilds and PKs, family ties and friendships, Naoki's life is certain to change from ALO, whether for good or bad.
{I do not own Sword Art Online, or anything official related to it. This is my interpretation of a possible story after season 2 of the anime. I do not own the cover art.}