The term "Osamedono" means a palace where gold/silver, costumes and/or furnishings were kept. It was the origin of nando (storage room) in subsequent years.
At the Imperial Palace, according to "Seikyuki" (volume 8, shoshoji), Giyo-den, Kurodo-dokoro/Ryoki-den and Jiju-den were used as Osamedono for inherited Imperial treasures, other general Imperial treasures and papers/folding screens respectively. Other than the above, the fact that Shunko-den was also used as Osamedono was recorded in "Nihon koki" (Later Chronicle of Japan) (dated December 2nd of the fourth year of Jowa era) and "Sandaijitsuroku" (the sixth of the six classical Japanese history texts) (dated February 21st of the eighth year of the Gangyo era). Such Osamedono were managed by Kurodo-dokoro, the office of Imperial household logistics, and its officials like kurodo (Chamberlain)/zoshiki (low-level functionary) were in charge of actual administration. Further, it is believed that Osamedono also existed at Koryo-den.
Similar facilities existed also at the residence of court nobles and temples. According to "Imakagami," Osamedono existed at the residence of FUJIWARA no Morozane and MINAMOTO no Masazane and according to "Azumakagami" (dated June 17th of the first year of Antei era), Osamedono was constructed at the residence of seii taishogun (literally, "great general who subdues the barbarians").
Further, Osamedono at the residence of Hikaru Genji appeared in 'Suma' of "The Tale of Genji"
Instead of Osamedono, the term 'nando' came to be used from the Muromachi period.