美少年 (biɕoꜜːneɴ; also transliterated ) is a Japanese term literally meaning "beautiful youth (boy)" and describes an aesthetic that can be found in disparate areas in East Asia: a young man of androgynous beauty. This word originated from the Tang dynasty poem Eight Immortals of the Wine Cup by Du Fu. It has always shown the strongest manifestation in Japanese pop culture, gaining in popularity due to the androgynous glam rock bands of the 1970s, but it has roots in ancient Japanese literature, the androsocial and androerotic ideals of the medieval Chinese imperial court and intellectuals, and Indian aesthetic concepts carried over from Hinduism, imported with Buddhism to China. Today, are very popular among girls and women in Japan. Reasons for this social phenomenon may include the unique male and female social relationships found within the genre. Some have theorized that provide a non-traditional outlet for gender relations. Moreover, it breaks down stereotypes surrounding feminine male characters. These are often depicted with very strong martial arts abilities, sports talent, high intelligence, dandy fashion, or comedic flair, traits that are usually assigned to the hero/protagonist role.
The prefix bi (美) more often than not refers to feminine beauty, and bijin, literally "beautiful person", is usually, though not always, used to refer to beautiful women. 美中年 means "beautiful middle-aged man". Biseinen is to be distinguished from bishōnen as 青年 is used to describe men who are of age, including those who have entered or completed tertiary education. The term shōnen is used to describe boys of middle and high school age. Last, bishota can be used to refer to a beautiful, pre-pubescent male child or a childlike male. Outside Japan, bishōnen is the most well-known of the three terms, and has become a generic term for all beautiful boys and young men.
The aesthetic of the bishōnen began as an ideal of a young lover, originally embodied in the 若衆, or adolescent boy, and was influenced by the effeminate male actors who played female characters in kabuki theater.