Jun Arata finds his missing sister's old notebook — and its handwriting matches Ghostwright, the legend of the underground coding duel scene.

Obata finally talks about Ghostwright and his own past in The Build — and Jun decides to duel himself, only to choke badly on his first real attempt.

Obata calls in Kanade, a former top-bracket duelist, to train Jun for real — and names a qualifier round that turns the arc's stakes concrete.

A flashback shows who Sana really was before she vanished, intercut with Jun's present-day training — and a detail in her notebook's margins finally rattles Kanade.

Kanade reveals what Halcyon really is and why she quit dueling, Rin's brother thread finally cracks open, and a warning arrives that entering the qualifier means being seen by the wrong people.

Jun's first real competitive duel, against a sharp rival named Ren — and the moment it ends, Halcyon finally makes direct contact.

The stranger from the qualifier identifies herself and forces the group to confront what Halcyon really wants — and reveals Sana may still be alive.

The group investigates the location of Sana's last confirmed sighting and finds proof she was building something specific before she vanished again.

The group reaches the old Halcyon holding at Sakuragaoka — and Sana finally appears, alive, in the present.