"Umi Yukaba" (roughly, "Going Out to Sea") was the anthem of the Imperial Japanese Navy during World War II. A slow, mournful tune, its lyrics were taken from a poem written by Otomo no Yakamochi way back in AD 749 - "the poem celebrating the imperial edict on the discovery of gold in Michinoku province." The poem is from the Manyoshu, an anthology containing the oldest known poems in the Japanese language.
The song took on specially meaning to the kamikaze pilots. When a kamikaze squadron took off, the men left behind would sing "Umi Yukaba" as each plane departed, never to return.
Original manyogana (from poem 18:4094):
kusa musu kabane
okimi no hen
ni koso shiname
kaerimi wa seji
If I go away to sea,
I shall return a corpse awash;
If duty calls me to the mountain,
A verdant sward shall be my pall.
Thus for the sake of the Emperor,
I will not die peacefully at home.
Translation from: Rikihei Inoguchi and Tadashi Nakajima. Divine Wind: Japan’s Kamikaze Force in World War II. United States Naval Institute. Annapolis. 1958.