Vivy: Fluorite Eye's Song

Synopsis

Realizing that his virus failed, Tatsuya decides to head to Metal Float himself. Vivy is able to rescue Yugo and the other surviving Toak invaders and convinces him to retreat from Metal Float. Learning that Tatsuya is on the island, Vivy and Matsumoto confront him and he reveals his motives: while he fell in love with Grace like in the original timeline, due to the alterations made to history, she was converted into Metal Float's central core before he could propose to her. He also reveals that his attendant is merely a replica of Grace that he intended to transfer her consciousness into after the facility was shut down, but the virus has instead caused the island to go berserk due to it conflicting with Grace's programming. Ultimately, despite Tatsuya pleading with Vivy to help him save Grace, Matsumoto assures her that she is already beyond saving and she reluctantly resolves to euthanize her to avoid further casualties. Vivy then proceeds to fight her way to the core and successfully destroys Grace, finally shutting Metal Float down. Afterward, though, a grief-stricken Tatsuya commits suicide, causing Vivy to suffer a mental breakdown.

(Source: Wikipedia)