Told mostly from Kallen's perspective, her rocky relationship with her biological mother is revealed. The Black Knights are sent on a mission to take out the drug "Refrain", and find themselves to be popular among the Elevens. Kallen's mother is found among the Refrain users, and is arrested following the Black Knights' destruction of the drug stockpiles. Kallen promises to have changed the world by the time she is released.

The Black Knights' assault on the Britannian Army in Narita proves successful, and Cornelia is cornered by Kallen and Lelouch. The army is pinned down by the Japan Liberation Front when they attempt to assist her. At Euphemia's request, Suzaku rushes onto the battlefield in the Lancelot to rescue Cornelia. He saves Cornelia and manages to corner Lelouch. C.C. comes to Lelouch's rescue by mentally traumatizing Suzaku, but is injured when Suzaku begins firing wildly. As he takes care of her, Lelouch inadvertently learns her real name. The Black Knights retreat from the conflict in victory, leaving the Japan Liberation Front and the Britannian Army to fight amongst themselves.

An inauguration ceremony of Clovis' memorial art museum is being held, with Euphemia judging the art works. Lelouch agrees to help Kyoshiro Tohdoh's comrades rescue their leader and Shirley finds an old crumpled letter detailing her previous knowledge of Zero's identity. During the rescue mission, Lelouch convinces Tohdoh to join the Black Knights. The Lancelot appears and attempts to stop them, but Lelouch is able to predict its movements and plan a counterattack. When Tohdoh slices open the cockpit, revealing Suzaku within, Lelouch is shocked, having originally planned for Suzaku to become Nunnally's knight. He orders an immediate retreat as reinforcements arrive. Seeing Suzaku's bravery and creed, Euphemia announces to the media that he will be her knight.

As Euphemia knights Suzaku, Lelouch establishes the hierarchy of the Black Knights. Diethard Reid suggests assassinating Suzaku, but Lelouch has other plans for him. He launches a plan to disable and capture Suzaku and the Lancelot at a Britannia military base on Shikinejima. The plan almost succeeds, but Second Prince Schneizel el Britannia appears and orders his floating battleship, the Avalon, to bombard the island.

The Britannian Army fights back against the Kyūshū invaders with the Lancelot. Meanwhile, Nina meets Princess Euphemia and inadvertently gives Euphemia peace of mind about her feelings for Suzaku. As Suzaku becomes cornered when his Lancelot's battery runs out, Euphemia encourages Suzaku to fight on and live. Zero and C.C. fly into the battlefield in the Gawain to recharge the Lancelot, and the two Knightmares end the Kyūshū campaign together.