Iimoriyama: Samurai Suicide in Aizu-Wakamatsu
They saw fire coming from the town, and wrongly thought that their castle had been captured. Here, they commited harakiri (or seppuku, as is more commonly used in Japan) - suicide by disembowelment. There were 20 samurai on the mountain who attempted suicide, one of which survived. A memorial on the mountain was set up to honor their legacy.
When people think of the concept of samurai loyalty, this example is probably the most referenced; these young soldiers would have rather died than live with the enemy.
Iimoriyama is easily accessed by taking the Aizu loop bus to Iimoriyama-shita. The Memorial Hall and Folklore and Historical Museum each cost 400 yen, and are open from 8:00-17:00 April through November, with reduced hours in the winter months. Sazaedo Pagoda also charges a steep 400 yen admission, and is open from 8:15 until sunset April through December, and 9:00 to 16:00 January through March. The shrine, tombs, and lookout point are free, although using the escalator adds a couple hundred yen to your visit.