Alex-in-Evanston said:
I can't imagine something more difficult to tattoo than transparent water. What's the story with the underwater dragon?
The story? Ah, that is long and complicated, involving ongoing gods stuff and the sword of the emperor. And not quite as heroic as depicted, but that is what artistic license is all about, right?
Main story of the print:
Susanoo-no-mikoto, expelled from Takamagahara, descended to Mt.Sentsu in Izumo district, which is called Torikami.
Then, to his surprise, a chopstick came floating down the river. from upstream. Thinking that there must be people living upstream, Susanoo-no-mikoto walked up the river.
There an old couple named Ashinaduchi and Tenaduchi were crying with a beautiful young woman named Kushinada-hime between them.
When Susanoo-no-mikoto asked why, the old couple explained that they had eight daughters, but an eight-headed, eight-tailed serpent had come to eat their daughters one by one every year for the past seven years and that it was now the time for him to come and eat their last daughter.
They said that the serpent's eyes were like red cherries, his one body had eight heads and eight tails, his length was such that he spanned eight valleys and eight mountain peaks, and his appearance was really horrible.
Listening to the story, and fascinated by Kushinada-hime's beauty, Susanoo-no-mikoto made a deal that if they let him marry their beautiful daughter, he would kill the serpent.
Susanoo-no-mikoto turned Kushinada-hime into a hair-comb, and placing this in his hair-bunch, asked Ashinaduchi and Tenaduchi to make eight doors in the fence and place eight barrels of strong sake (rice wine) at each door.
Before long the eight-headed serpent came, drank the sake with relish, and becoming drunk, lay down and slept. Then Susanoo-no-mikoto took out a sword and hacked the drunken serpent. Finally he killed the serpent and hacked it into pieces, upon which a fine sword appeared from its tail.
http://www6.pref.shimane.jp/kodai/en/shinwa/a_susano/sa_3.html
And that sword he found in the tale?
The Kusanagai no Tsurugi
Recorded in the Kojiki,(record of ancient matters) and the Nihon Shoki (The Chronicle of Japan) the oldest existing written records of Japanese history, is the story of the imperial regalia sword of the Japanese Emperor. Written in the eighth century, most of its early records are considered to be mythical. It is written that the storm God Susanoo no Mikoto slayed an eight-headed and eight-tailed giant serpent called Yamata-no-Orochi whilst saving Princess Kushinada-hime. Susanoo got the serpent drunk on sake and killed it. Then, as he cut open its tails, he found a sword (known as Ama no Murukumo no Tsurugi - The Heavenly Gathering of Clouds Sword) that he presented to his sister Amaterasu Omi Kami the Sun Goddess.
Amaterasu later gave the Ama no Murukumo no Tsurugi to her grandson Ninigi, when he came down to Earth. Ninigi in turn gave it to his great grandson Emperor Jimmu (The first emperor of Japan) along with a mirror and jewel (magatama). These three treasures came to be known as the Imperial Regalia: symbols of imperial authority and legitimacy, providing the link between the imperial family and their divine ancestry. According to The Nihon shoki, Ise shrine was established by Yamato-hime no Mikoto, the daughter of the legendary Emperor Suinin (reigned ca 29 B.C. to 70 A.D.), as a residing place for the Imperial regalia. She later loaned the sword to her nephew Prince Yamato Takeru no Mikoto when he was leaving to subjugate the Ainu.
A famous account of Prince Yamato Takeru no Mikoto and the Ama no Murukumo no Tsurugi came when he was surrounded by the Ainu whilst hiding in the long grass. The Ainu set fire to the grass in order to flush him out or kill him. Prince Yamato Takeru used the sword to cut down the grass and escaped. Accounts of this event vary slightly with another version, which implies that the sword had magical powers and flew out of the scabbard by itself to cut down the long grass - thus saving the young Prince. From this time onward the sword was to be known as the Kusanagi no Tsurugi (The Grass Cutting Sword).
This sword was to be the subject of more controversy in 1185 at the Battle of Dan-no-Ura, the culmination of the Gempei wars between the Taira and Minamoto clans. The three items of the imperial regalia were thrown into the sea when the child Emperor Antoku drowned in the arms of Nii Dono, wife of Taira Kiyomori. Legend has it that the Jewel and Mirror floated to the surface and were saved but the sword was lost. Later accounts report that this was not the actual Kusanagi no Tsurugi, but a copy and that the original still resides in Atsuta Jingu in Nagoya to this day.
http://www.traditionaloshigata.com/articles/kusanagi.htm
The dragon in the print and tat does have smaller heads behind the main one, and Kyosai did represent the serpent as a dragon. And he kind of eliminated the "get it drunk and sneak up on it" part of the tale. Makes for more dynamic art that way.