Lord Yupa, also known as Yupa Miralda or Master Yupa (DE1 pg 15 first appearance and unidentified, pg 21 identified), is a human wanderer/explorer with a large bushy mustache. He's a master swordsman, considered the best in the Periphery, and teacher of Nausicaa. He is a longtime friend of King Jihl and often visits the Valley of the Wind with his two horseclaws, Kai and Kui.
He first appears in the manga and the movie when he is being chased by an enraged Ohmu. He is unidentified at first because he's wearing a Shohki Mask to protect him from the miasma of the Sea of Corruption.
Yupa uses his gun in the jungle because he thought an insect had a human baby, but it was only a fox-squirrel, and that is why he is chased by the rage-filled Ohmu.
Nausicaä's quick thinking (including some strobe grenades and a worm-flute) aids him in escaping the giant insect. The friends are re-united and the rescuted fox-squirrel becomes Nausicaä's companion Teto.
Later, at the Castle in the Valley of the Wind, he gave out various gifts to the community.
Yupa talks with Jhil about Nausicaä and about the world, noting that he had witnessed too many attack of herds of Ohmu on human villages and scattering of spores (DE1 pg 90)
After Nausicaä leaves to fight in the Periphery Campaign, Yupa departs the Valley to continue searching for what he's been looking for for years (DE1 pg 89)
Found a spot in the heart of the forest in his youth that was purportedly "a barren desert of sand, burned and corrupt with poisons" that was the final stage of the Sea of Corruption, a climax forest, where he found sand that was free of poison and of metals unknown and he suspected people are unable to forge it (DE1 pg 90-91) believes hypothetically Sea of Corruption is cleaning up the poisons (DE1 pg 90-91). Jhil doesn't believe he'll see Yupa again (DE1 pg 91)
Film Version of Yupa:
After being saved by Nausicaä, Yupa tells King Jil that a few more kingdoms were swallowed by the jungle. Jihl asks Yupa to help him rule the Valley of the Wind, but Obaba says that Yupa must look for something.
After a thousand years of darkness, he will come. Clad in blue and surrounded by fields of gold to restore mankind's connection with the Earth that was destroyed; and he will guide the people of this planet at last to a land of purity.
He also tells Mito that he heard that a giant warrior from the Seven Days of Fire was under Pejitei, and it was dormant for a thousand years (it was on the Torumekian warship that crashed along with Lastelle, a princess from Pedjite that was a hostage).
Lord Yupa also stopped Nausicaä from killing Torumekian soldiers so he could say that the Valley tried to prevent their ship from crashing, and had finished burying the dead. Also, he said that they need a good reason for war, and to show courtesy and respect. Later in the movie, he found Nausicaä''s secret room and found out what she was going to do (King Jihl gets shot).
When Nausicaä was taken to Torumekia, Yupa finds out the Torumekians are bringing the warrior back to life, and hears that the plane went down. Yupa and Mito go in the Valley's Gunship to look for the princess, and when they found her, Yupa jumps onto the Pejjitei ship, and starts to fight the Torumekians.
After the battle, the Pejitei plane heads to the Valley of the Wind, and Yupa sees eyes turn from red to blue. He also sees the legend come true.