Aiko, Princess Toshi (敬宮愛子内親王殿下, Toshi no miya Aiko naishinnō denka?), born December 1, 2001, is the first child of Their Imperial Highnesses Crown Prince Naruhito, heir apparent to the Japanese throne, and Crown Princess Masako.

Aiko, the princess's personal name, is written with kanji character for "love" and "child" and means "a person who loves others." She also has an imperial title, Princess Toshi (敬宮 toshi no miya) which means "a person who respects others." This formal title will be dropped if she marries a commoner. The Imperial Household Law of 1947 abolished the Japanese nobility; and under provisions of this law, the imperial family was streamlined to the descendants of Emperor Taishō.

In a break with tradition, the name was chosen by her parents, instead of by the emperor. It was selected from the teaching of the Chinese philosopher Mencius. It reads "A person who loves others will be loved by others, and a person who respects others will always be respected by others."