Chapter 99

The graduation party empties as sirens wail, and Henry releases Martha's hand so everyone can reach the shelter. The alarm proves false, but the celebration is called off, and when Henry asks what she had wanted to say, Martha loses her nerve and requests only that he see her off. That send-off never happens: her letter naming when and where she would depart reaches him so heavily censored that he never learns the details, and she leaves the station alone. A follow-up letter survives the redactions, and the pair settle into a steady correspondence even as the fighting worsens and her replies thin out.

When the front deteriorates, the Women's Defense Auxiliary is told a combat battalion will be formed and given one night to volunteer. Amid rumors that deserters face execution, Martha steps forward, reasoning that if death is coming anyway she will meet it defending Ostania. Newspapers announce the Women's Combat Battalion with her photograph on the front page, horrifying Henry back in Berlint. At a school debate on whether humanity can escape war, a young Donovan Desmond argues the negative, calling human beings liars whose hidden motives doom history to repetition, but Henry barely listens, consumed by worry.

A final letter arrives in which Martha admits her mistake and longs to see him again; Henry, weeping, realizes too late that he wanted to be her protector. Then the letters stop. While carrying his own desperate reply to the post, he hears a radio bulletin declaring the battalion annihilated. When the military later stages a recruitment speech at Eden that exploits the dead women as propaganda, a ragged Henry publicly shames the speaker and condemns the war, an outburst that gets him branded a traitor and jailed. His father visits the cell and orders him to behave or forfeit his teaching post, and Henry grudgingly complies, choosing to pursue the peaceful future Martha described in her last letter rather than cling to pride. An eye injury from the arrest leaves him wearing his signature monocle. Donovan later tells him a fool should expect nothing from people; Henry answers that abandoning everyone would end human history, and the boy surprises him by admitting he enjoys the lectures. After the armistice Martha never returns to Berlint, and Henry, pressed by his father, marries a chosen suitor. In a lone seaside cabin close to the frontier dividing East from West, Martha rests and recovers, alive.

Martha's graduation-night confession fails a second time, and censored mail sabotages her planned farewell at the station. The two maintain a long correspondence until Martha volunteers for the newly created Women's Combat Battalion, whose destruction is later announced over the radio. Henry is arrested for denouncing the war during a military recruitment event at Eden Academy and starts wearing a monocle after his eye is hurt in custody.

A school debate introduces the young Donovan Desmond and his belief that people are inherently deceitful, an early glimpse of his adult philosophy. Henry ultimately marries a woman arranged by his father, while the closing page reveals Martha survived and is recovering by the sea. Martha's mother, Henry's father, and Lucia debut in this chapter.

Mission 99 spans 28 pages in Volume 14 and concludes the Love and War Arc flashback begun in the preceding chapters. The cover assembles Mr. Fowler, Henry Henderson, and Martha Marriott. Its chapter illustration references a sketch of Anya drawn by Takuya Eguchi, Loid's voice actor, during a SPY x FAMILY anime event alongside the "Anya's Drawing Song" video.