SI-VIS: The Sound of Heroes Episode 13: Each of Our Despair and Resolve

A dark void opens, and Seiren lies still, held by a weeping figure. Their words speak of a failure, of letting her fight alone. It is a memory, or perhaps a premonition, painted in grainy, distorted colours. This opening sets a somber, urgent tone for what is to come. The past is not past; it is a weight.

City screens flash news of Seiren's critical state. Medis walks with purpose, though her stoic face betrays little. Her path is crossed by Xenos, whose bright shirt and casual banter stand in sharp contrast to the unfolding crisis. Later, in a sterile hospital room, Medis and Hayama examine scans of a blue, triangular shard near Seiren's heart. Hayama explains it is a Zenith curse, slowly erasing Seiren’s "Idea" and her very existence.

In the control room, Kyoya remarks on Seiren's stubbornness as her only lifeline, drawing a sharp response from Rui. This tension between them highlights a deeper friction. Meanwhile, Nagi pushes herself to exhaustion in the recording studio, her voice raw with desperate intensity. Rui and Miyu watch from beyond the glass, their faces reflecting the true cost of Nagi's drive to prove herself.

Medis and Xenos continue their walk, their conversation turning to the concept of "Idea" and its emission from humanity. Xenos observes the crowds, suggesting their raw, uncoordinated energy might be the key to saving their own world. Medis remains unconvinced. Their exchange hints at a larger, cosmic struggle for spiritual resources, making this Earth more than just a battleground.

Under the moonlight in a quiet park, Nagi continues to practice her singing. Miyu finds her, offering water and gentle words of caution against carrying the group’s burdens alone. Nagi confesses her desire to become strong, to be a pillar for Kyoya. Their shared vulnerability on the stone bench, ending in a quiet hug, solidifies the bonds forged in crisis.

Back in the studio, Nagi's singing reaches a new crescendo, her heart pouring into the melody. A brilliant, multi-colored aura erupts around her, a visual manifestation of her evolving "Idea." Rui witnesses this with shock, recognizing a profound awakening. Simultaneously, Rui finds a mysterious CD, a path to deeper truths, and enters the high-security server room to uncover its contents.

Within the server room, Rui activates a hidden archive. A holographic projection flickers to life, showing a younger Kyoya, then called Yosuke, protecting a terrified young Nagi ten years prior. Military helicopters and dark energy beams devastate their island home. Yosuke's powers create a shield against the onslaught. This flashback confirms Kyoya and Nagi are survivors from another world, explaining Kyoya’s fierce protectiveness.

A holographic Yosuke, the younger Kyoya, then addresses Rui directly. He explains his decision to keep their past secret, wishing for Nagi to have a normal life, free from the wars of their home world. He places his trust in Rui, entrusting her with Nagi's future and the S/V-S project. Rui is overwhelmed, the weight of Kyoya's long-standing sacrifice settling heavily upon her.

Rui, tears still wet on her cheeks, returns to the training area. She watches Nagi, Miyu, and Crios (now Apollo) train with renewed vigor, unaware of the truths she now carries. Nagi declares her unwavering determination to forge a "new S/V-S," a place where no one suffers alone. She stands firm in her goal to be Kyoya’s home, carrying the weight of her conviction forward.

The episode shifts abruptly to a bonus segment, featuring a peculiar, large bird mascot named Kujima. He interacts with a schoolboy, Arata, engaging in various surreal, comedic antics. Kujima eats onigiri, causes minor chaos in a supermarket, and lounges casually in Arata’s room. This lighthearted sequence provides a stark, almost jarring, tonal shift from the dramatic events preceding it.