Spiral: The Bonds of Reasoning Vol 14

From the Yen Press edition

When Kirie's DNA tests on Ayumu, Hizumi, and their respective older brothers yield shocking results, the disgruntled Watcher confronts the only two people who can confirm the truth of Ayumu's parentage: his mom and dad. What she learns shakes her to the core, but how will Ayumu react when Hizumi reveals how science has warped their fates? Will Ayumu's resolve to save the Blade Children remain firm, or will anger and despair cause him to waver?

Source: Yen Press