He was a Japanese daimyo, who ruled over the Shimazu clan and directed them in their ways of life.

Shimazu Tadayoshi (島津忠良; October 14, 1493-December 31, 1568) is a daimyo who ruled Satsuma Province.

He was born in a spin off clan of Shimazu clan, Mimasaka Shimazu clan(伊作島津家) but after his father Shimazu Yoshihisa died, her mother married Shimazu Unkyu of another spin off clan, Soshu clan(相州家). Tadayoshi came to represent two clan within Shimazu clan.

Shimazu Katsuhisa who presided over Shimazu clan did not have a son and he was driven out by Shimazu Sanehisa who was the head of Sasshu clan(薩州家). Sanehisa claimed to be the head of clan without properly being recognized by rest of clan. Tadayoshi had his son Shimazu Takahisa be adopted by Katsuhisa and on 1539 in the battle of Ichirai, Tadayoshi defeated Katsuhisa and had Takahisa be recognized by all member of Shimazu clan as the head.

After the succession by Takahisa, Tadayoshi retired to Kaseda of Satsuma Province. Yet he held actual power and had a trade with Ryukyu Kingdom and Ming Dynasty, massive purchases of matchlock rifles to make the clan prosperous for the eventual near unification of Kyushu by Takahisa.

Tadayoshi made a Iroha Uta poetry which sung the importance of unity. It begins with following words.

Inishie no Michi wo Kikitemo Tonaetemo Waga Okonai ni sezuba Kahinashi

It means "Even if you learn old ways, if you cannot use it as your own, it is meaningless". It was based on Confucianism and his educational philosophy would deeply influence his four grandsons, Shimazu Yoshihisa, Shimazu Yoshihiro, Shimazu Toshihisa, and Shimazu Iehisa. It would eventually make it way into modern philosophies in Meiji period as Satsuma han would take part in modernizing Japan.

He called himself Shimazu Nisshinsai in later years and praised his four son as "The leader Yoshihisa, the brave Yoshihiro, the planner Toshihisa, and the tactician Iehisa". He died on 1568.

Shimazu Takahisa (島津貴久; 1514-July 15, 1571) was a daimyo during Sengoku period. He is the fifteenth of Shimazu clan and the son of Shimazu Tadayoshi.

On 1526, Takahisa was adopted as a son of Shimazu Katsuhisa to become the head of the clan. He successfully united the clan again winning battles against Satsuma branch of the Shimazu clan. He launched series of campaigns to reclaim three provinces, Satsuma, Osumi, and Hyuga which made some starts but it would be up to the next generation to succesfully reclaiming them. He nurtured such future leaders like Shimazu Yoshihisa, Shimazu Yoshihiro, Shimazu Toshihisa and Shimazu Iehisa who would make the Shimazu clan take over the entire island of Kyushu.

Takahisa actively promoted relationships with foreign person and countries. On 1549, he granted Francis Xavier, the protection to spread Christianity in his domain. He also held a diplomatic relationship with Ryukyu Kingdom

Shimazu Yoshihiro (島津義弘; August 21, 1535-August 30, 1619) is the second son of Shimazu Takahisa and younger brother of Shimazu Yoshihisa. It had traditionally been believed that he became seventeenth head of Shimazu clan after Yoshihisa but it is currently believed that he let Yoshihisa keep his position.

He was a skilled general and the victory against Ito clan at the battle of Kigasakihara on 1572 is counted as one of his many victories. He contributed greatly to the unification of Kyushu. On 1587, facing Toyotomi Hideyoshi's troop that seeked to pacify Kyushu, Yoshihiro pressed for a war even after his brother and the head of clan Yoshihisa surrendered. After Yoshihisa repeatedly asked for the surrender, Yoshihiro finally did surrender. After Yoshihisa became a Buddhist monk, it had been believed that he became the head of the clan but the real power remained in Yoshihisa's hands.

He had been a willing and a skillful general for Hideyoshi. On both 1592 and 1597 of Seven-Year War, Yoshihiro set his foot in Korean peninsula and successfully carried out series of battles. On 1597, working together with Todo Takatora, Yoshihiro defeated Won Gyun's navy killing the commander Won Gyun in the battle. At the battle of 泗川 in 1598, facing Ming army counting 37,000, Yoshihiro defeated them with only 7,000 troop and killed several thousands in the battle. Shimazu troop under Yoshihiro was called "鬼石曼子" by Ming. On the final battle of the war, battle of Noryang when the truce had already been signed, Yoshihiro managed to fatally wound Yi Sun-sin and to retreat back to Japan.

For the Battle of Sekigahara on 1600, Yoshihiro was supposed to take the side of Tokugawa Ieyasu, but he crushed against Torii Mototada on arriving for a rescue at Fushimi Castle and after being humiliated, took the side of Ishida Mitsunari instead. Yet Yoshihiro could not get along with Mitsunari as well, who did not listen to any of Yoshihiro's plan including surprise night attack on the day before the actual battle. On the day of the battle, Yoshihiro and his troop of 1500 simply held ground and did not fight at all. After rest of Mitsunari's side was wiped out, Yoshihiro was stranded in at least 30,000 of Ieyasu's troop. Vastly outnumbered, Yoshihiro tried to make a charge against Ieyasu himself but after Shimazu Toyohisa demanded that he not kill himself over a meaningless battle, Yoshihiro instead chose to charge straight through Ieyasu's troop to make an exit at the other side. By having his troop make a fighting retreat called Sutegakari(捨て懸かり) where until certain number of men died holding a position and repelling an attack, the main body of army fought as well. Toyohisa and the bulk of troop died, but the charge and the retreat was a success and fatally wounded Ii Naomasa. After beating back the chase, he picked up his wife at Sumiyoshi of Settsu Province and returned to Satsuma Province by ships.

After recognizing why and how Yoshihiro behaved on the battle field, Ieyasu had Shimazu clan retain its domain and let Yoshihiro's son Shimazu Tadatsune succeed him. Yoshihiro retired to Sakurajima and took up teaching younger generations. He died on 1619 and several of his retainers who had fought along him followed him by committing suicide.

Yoshihiro was essential to Shimazu clan and both Ieyasu and Hideyoshi tried to divide the clan by treating Yoshihiro well, but treating the elder brother Yoshihisa badly which did not succeed. He was a devoted Buddhist, and built a monument for enemy troops during Seven-Year War.