Nikki bungaku (日記文学) is a genre of Japanese diary literature including prominent works such as the Tosa Nikki, Kagerō Nikki, and Murasaki Shikibu Nikki.

While diaries began as records imitating daily logs kept by Chinese government officials, private and literary diaries emerged and flourished during the Heian period (794-1192 AD).

Although scholars have found diaries dating back to the eighth century, most of those were mere records kept on daily matters of state.

At that time, Japan looked to China as a model of culture and civilization and sought to copy Chinese official government diaries. Thus, early Japanese diaries were factual, written in Chinese characters, and influenced by official, male perspectives.

Ki no Tsurayuki (872?-945), a famed poet and author, is credited with writing the first literary diary.

His Tosa Nikki, written in 935, records his journey from Tosa in Shikoku to Kyoto through the alleged perspective of a female companion.

Departing from the tradition of diaries written in Chinese, Tsurayuki used vernacular Japanese characters, waka poetry, and a female narrator to convey the emotional aspects of the journey.