The day before. During SAO, Kirito proposes to Asuna and they decide to honeymoon in Aincrad. But when they arrive where they expect to find their new home, they can't believe their eyes...One day later. Ever since Asuna began using a new character in ALO, she has been constantly tormented by mysterious attacks of alienation, the source of which lies in one of the SAO tragedies... Rainbow Bridge. Kirito and his friends successfully survived the journey to the underwater temple. However, a mysterious dialogue between the ruler of the seas, Leviathan, and the ruler of the depths, Kraken, calls them to a new adventure! Prayer of the sisters. The tragedy of SAO had not yet come to an end when one girl agreed to become a test subject in tests of the Medicuboid, a total immersion medical device. Thus begins the story of Ultimate Sword Yuki.