The term "Naiju" means children officials who was engaged in miscellaneous jobs at the Imperial palace in the Nara and Heian periods. They were placed under the supervision of Naijudokoro (Imperial Pages Office) (under Naijusho for a short period), one of Ryoge no kan (a post outside of the Ritsuryo code). Its Japanese reading is 'chiisana warawa' (little children).
It is said that children who served at the Imperial palace were called Naiju in ancient times. They were engaged in security and other miscellaneous jobs at the Imperial palace night and day, attended court functions like sechie (seasonal festival), reported time to the emperor and conveyed the order of the emperor or sanko (Grand Empress dowager, Empress dowager, Empress) to relevant officials.
Though the time of the establishment of Naiju system is unknown, they were initially called Jushi and were placed under the supervision of Jushidokoro (predecessor of Naijudokoro). (According to Norinaga MOTOORI, the official post called 'Naiju' first appeared in the Tenkanhen of "Rites of Zhou," and children called 'doju' already existed in Japan in the era of the Emperor Ankan ("Rekicho Shoshikai" (commentaries on Imperial edicts in the Shoku Nihongi)). In the meantime, the term "Naiju" was also used as the other name for eunuch during the Tang Dynasty in China. In a document preserved at Shoso-in, Fukushin KOMANO and KAZURAKI no Henushi (the husband of WAKE no Hiromushi) were recorded as Jushi who conveyed in 757 the message of zojishi (an official in charge of building temples) to the Empress Dowager Komyo requesting her to provide gold dust to paint the statue of Birushana Buddha in Todai-ji Temple. Both of them were government officials (Fukushin was shohitsu (assistant director) and Henushi was shochu (junior inspector)) belonged to Shibi chudai (the office of the Empress Dowager Komyo).
In 763, Jushi was renamed Naiju and Jushidokoro was also renamed Naijudokoro (later Naijusho). Naijudokoro was abolished in 772, but it was reestablished later as a small office called Naijuzoshi. However, it was again abolished on November 23, 807 ("Ruiju Kokushi" (Classified National History)). On February 5, 811, it was once again established under Kurododokoro (Board of Archivists) ("Nihon Koki" (Later Chronicle of Japan)). According to Daijokanpu (official documents issued by the Grand Council of State) issued on June 9, 820, the reason for the reestablishment of Naiju was because the number of Otoneri (Imperial Attendant) was halved from 800 persons ("Ruiju sandai kaku" (Assorted regulations from Three Reigns)). From the above, it is presumed that Otoneri took jobs of Naiju during the period when Naiju didn't exist. It is said that there were two categories of Naiju, namely those who were allowed to enter the palace and those who were not allowed to do so.
The prescribed number of personnel in the Nara period is unknown, but it was 100 for each of the Left and Right Otoneriryo (Bureau of Imperial Attendants) at the time when Naiju system was abolished from 806 and 810 and 120 at the time of reestablishment from 810 and 824. According to "Engishiki" (codes and procedures on national rites and prayers) and "Wamyoruiju-sho" (Kango (Chinese language) -Japanese Dictionary in mid Heian period), the prescribed number of personnel was 200 and 300 respectively.