Aihime (her name also can be pronounced Yoshihime or Megohime) (1568 - February 21, 1653) was the only daughter of Kiyoaki TAMURA and a lawful wife of Masamune DATE. Her mother was Okita, a daughter of Akitane SOMA. His ingo (a title given to a Buddhist) is Yotokuin.
She married Masamune DATE in her twelfth year in 1579. Unfortunately, her wet nurse was killed by Masamune who suspected that betrayers from the Tamura clan were involved in the assassination attempt on him. It is said that her marriage got worse for a while because many other waiting maids serving her were executed. But then, her marriage seemed to be restored and she gave birth to Irohahime (Tadateru MATSUDAIRA's wife) in 1594 after she moved to the Date residence in Jurakudai (government office/residence) in Kyoto. Then, she had four children of Masamune, including Tadamune DATE (the second lord of the Sendai Domain), Munetsuna DATE, and Takematsumaru DATE.
Since the Tamura family had no daughter other than Aihime, when Aihime married Masamune, the agreement was reached that the Tamura family would adopt the second son of them, but the second son, Munetsuna died young at the age of 16. Since the third son, Takematsumaru died young too, the Tamura clan had to wait for its revival until the generation of Muneyosi, the third son of Tadamune.
Even after she lived in the Date residence in Jurakudai (government office/residence), she might have played a role like, what is called, a woman diplomat to inform Masamune of the Kyoto situation, saying, "the world has not been stabilized yet. You should decide your course of action in accordance with the cause of the universe. Don't worry about me. I always have a knife with me. I'll promise not to be shamed" in her letter to support Masamune.
When Masamune died on May 24, 1636, she entered the Buddhist priesthood under the Ungo Zenji and called herself Yotokuin. Before the 7th anniversary of Masamune's death, a wooden statue of him was created by the order of Aihime and it is a valuable historical material to tell his looks.
She died at the age of 86 on January 24, 1653. It was the same day as the monthly anniversary of Masamune's death.
Her graveyard is the Yotokuin (mausoleum) near the Zuigan-ji Temple. Ungo Zenji, a doshi (ceremony leader), left the word about Aihime which tells her character, saying "she managed a household very well and was a merciful wise wife." The statue of Aihime in a nun's attire kept in the Zuigan-ji Temple is beautiful and she seemed to be a woman as nicknamed "a beautiful princess". It is said that she was Christian temporarily.
The excavation research on the Zuihoden in 1974 showed that her husband, Masamune had B-type blood and her son, Tadamune, A-type blood, and therefore it is assumed that Aihime had A- or AB-type blood.