Before naming and launching ceremonies of the Imperial Japanese Navybattlecruiser 'Hiei', it carried the formal name of '卯号装甲巡洋艦 (U-gou armored cruiser)'. The Hiei was the second Kongou class battlecruiser / battleship, but 'U-gou' refers to the fourth sign of the Chinese zodiac, the rabbit. In the middle of the Russo-Japanese war, Japan had drawn up plans to build two battleships and four armored cruisers. However, because the war came to an end, the U-gou could not be built, unlike the other three armored cruisers - 'Ne-gou, 'Rat' cruiser "Tsukuba"', 'Ushi-gou, 'Ox' cruiser "Ikoma"', and 'Tora-gou, 'Tiger' cruiser "Kurama"'. After that, the navy reworked the plan for the ship to make it one of the Kongou class battlecruisers.
