Date Masamune was a regional strongman of Japan's Azuchi-Momoyama period through early Edo period. Heir to a long line of powerful daimyo in the Tōhoku region, he went on to found the modern-day city of Sendai. An outstanding tactician, he was made all the more iconic for his missing eye, and Date was often called the "One-eyed dragon".
Catching smallpox as a child, Date's eye withered and fell out of its socket and hung limply, so he plucked it out himself at the tender age of twelve. Blooded for combat at a young age he was married at 13, and won his first battle at 14, cutting his way through a rival clan with a sword in each hand. By the time he was 17, Date's father stepped down as Clan Leader and put Masamune in charge, sending the teenager out to command rampaging field armies of hardcore samurai and earn glory and honour for his family.
As head of Date Clan, Masamune was, first and foremost, a master of gaining territory through cleverness and intelligence. Focusing primarily on diplomacy, sabotage, and bribery, Date used spies, ninjas, and giant gold-laden treasure chests to gain territory wherever possible, but when blackmail and diplomacy failed, he was more than willing to carve the enemy asunder. He ruthlessly hunted down those who betrayed him.
Date Masamune never lost a campaign, was never beaten in one-on-one sword combat throughout his extensively-long career as a samurai warrior. He built his Clan into the north and was home to tons of gold mines and lucrative shipping ports. He mostly used these to trade the Europeans for firearms. Known for putting elaborate long, curved, gold-plated crescent moons on his helmets and marching his men in badass black armour with gold trim, it was the only armour capable of deflecting gunfire at the time.
At the end of the wiring states era, it was just he and Hideyoshi remaining, knowing Hideyoshi would defeat him in combat, he wore his finest clothes and faced the angry overlord, telling him that Date could "Be of some use." As Hideyoshi became shogun of all Japan, Date was the leader of the armies and lead Hideyoshi's more successful excursions into Korea.
When Tokugawa Ieyasu was on his deathbed, Masamune visited him and read him a piece of Zen poetry. Masamune was highly respected for his ethics; a still-quoted aphorism is, "Rectitude carried to excess hardens into stiffness; benevolence indulged beyond measure sinks into weakness."
He showed sympathy for Christian missionaries and traders in Japan. In addition to allowing them to come and preach in his province, he also released the prisoner and missionary Padre Sotelo from the hands of Tokugawa Ieyasu. Date Masamune allowed Sotelo as well as other missionaries to practice their religion and win converts in Tōhoku.
Date had converted to Catholicism, agreeing to convert after watching a Catholic missionary cure one of Date’s female friends of a horrid illness. So, Masamune decided he wanted to set up a trade route with Europe, and he built a western-style sailing ship and sent a delegation of Japanese nobles to Europe with a letter for the Pope and a couple ceremonial katana swords and on the route back became one of the first Japanese to cross the Atlantic. When the Tokugawa government banned Christianity, Masamune had to obey the law but his eldest daughter practised in secret.