They had waded through a dark, narrow ravine to get there — soaked, breathless, the sounds of the Battle of Tonoguchihara fading behind them. Twenty boys from the 白虎隊 (Byakkotai), the White Tiger Corps, had been separated from their unit in the fighting near Lake Inawashiro. Not yet adults. Not supposed to be front-line soldiers. They were the reserve force — the sons of Aizu's highest samurai families, held back precisely because they were considered too young and too valuable to spend in ordinary fighting. The battle had found them anyway.

They climbed Mount Iimori (Iimoriyama), a hill that looked out over the city of Aizuwakamatsu and, beyond it, Tsurugajō (Tsuruga Castle) — the seat of their lord, Matsudaira Katamori, daimyo of the Aizu Domain and one of the last men still fighting against the Meiji imperial forces. Katamori was thirty-two years old. He had refused to surrender for months while the rest of the Tokugawa coalition collapsed around him. The castle was the last thing standing.

From the hilltop, the boys could see the castle town burning. The wooden buildings of Aizuwakamatsu were on fire — houses, shops, streets they had grown up in. Smoke rose in columns so thick that the town itself became obscured. And somewhere beyond that wall of smoke stood Tsurugajō.

They could not see it clearly. They saw only the burning.

What followed was the logic of their upbringing taken to its absolute end. Their lord was surely dead or captured. The castle had fallen. There was nothing left to fight for, and surrender was not an option they had been raised to consider. Nineteen of the twenty drew their blades.

The White Tiger Corps had a name chosen from Chinese and Japanese cosmology: 白虎 (Byakko), the White Tiger, divine guardian of the west. A force of teenagers had been named after a sacred protector. That a domain needed its fourteen-to-seventeen-year-olds to carry that name said everything about how desperate the Aizu cause had become.

One of the twenty, Iinuma Sadakichi, had lied about his age to join. The 白虎隊 (Byakkotai) was supposed to be composed of boys sixteen to seventeen years old. He was fourteen. Born April 22, 1854, he was fourteen years old on the day he climbed Mount Iimori. When the others died, something went differently for him — his wound was not fatal, or the cold slowed the bleeding. A local woman found him on the hillside, still alive, and revived him.

The castle did not fall that day. It did not fall the next day, or the day after. Matsudaira Katamori held Tsurugajō for another twenty-nine days. The castle surrendered on November 6, 1868, when further resistance was genuinely impossible. Katamori himself was taken prisoner but was not executed. He was eventually pardoned and lived out his years as the chief priest of Nikkō Tōshōgū shrine — the Tokugawa's own sacred ground. He died in 1893.

Iinuma Sadakichi was the only person alive who could say what the nineteen boys had seen from the hilltop and what they had believed when they died. He told the story for the rest of his life. He died on February 12, 1931, at age seventy-six — sixty-three years after the morning on Iimoriyama.

For sixty-three years, he knew what his friends had not lived long enough to learn: the castle was still standing.