Shy returns to school only to find herself faced with Iko Koishikawa, a girl whose injuries she blames herself for. As if that wasn't stressful enough, a mysterious young boy sows discord and forces the girls to face the darkness in their hearts.

Koishikawa takes Momijiyama out on the town in an attempt to thank her for everything she's done for her. However, Momijiyama's introverted nature and shut-in lifestyle make this difficult. The two of them are then unexpectedly summoned by Unilord.

Shy faces off against Stardust for the right to remain a hero. To stand a chance, Shy has to discover what drives her as a hero and fuels the power of her Heart-shift bracelets. Heroes from the Black Cross help manage the aftermath.

As Shy searches for ways to strengthen the power of her heart, she finds support and inspiration in unlikely places. Help and begrudging assistance from Lady Black helps her understand struggle more as they help someone together.

Unilord sends Shy and Spirit on an urgent mission to the North Pole. There, they rendezvous with China's hero and work together to investigate the fate of researchers who had lost contact with the Arctic Base.

Iko and Pepesha share their experiences fighting Amarariruku, and new information about Stigma and his rings comes to light. Afterward, Shy faces an important aspect of being a hero: building up her image.

Teru travels to Russia to assist Pepesha's investigation into the mysterious girl they encountered at the North Pole. Not only are details about Pepesha's past brought to light, but new information leads to some disturbing implications about Tzveta.

The battle with Kufufu and Tzveta heats up as Shy and Spirit desperately try to get the civilians out of harm's way. Kufufu's unpredictable actions make her difficult to fight, and Tzveta's ice powers and inescapable heart make her a formidable foe.

As Tzveta regains her memories, Shy and Spirit witness the tragedy of Letana's adult life firsthand and learn how her ideals formed. The strength of her dark, frozen heart clashes against Shy's warm light.

Stigma's twisted endeavors have provided Pepesha and Letana the opportunity to finally say all the things they never could in the past. As their battle comes to a climax and close, much is revealed about their relationship and Stigma.

Reinforcements sent by Unilord arrive and assist in cleaning up the aftermath of the battle with Tzveta and Kufufu. Afterward, Teru ends up with an intense cold that leads Iko to look after her and realize just how normal heroes are.