Tonjiki refers to food given to lower officials or sometimes respectable persons at a banquet in the garden of the Imperial Court and nobles' residence during the Heian period. According to one theory, it was egg-shaped steamed glutinous rice.
Ton' means to gather and might indicate 100 or 200 pieces.
What Tonjiki was has been controversial.
According to 'Kakaisho' (Commentary on the Tales of Genji by Yoshinari YOTSUTSUJI), it was Tsutsumiii (rice wrapped in an oak leaf).
According to 'Teijo-zakki' (Teijo's memorandums), it was egg-shaped steamed glutinous rice.
It also says 'Since court nobles still call rice ball Donjiki, the person is from Kyoto.'
Therefore, it might mean rice ball in early-modern times.
A banquet was called Tonjiki in the old days. That there were two kinds of Tonjiki: Moritonjiki and Aratonjiki were noted in a passage of genpuku (attainment of manhood) ceremony of Crown Prince in 'Hokuzansho' (a representative book of ceremonies for the Heian period written by FUJIWARA no Kinto).
According to 'Ruijumeibutsuko' (an encyclopedia compiled by Matsuake YAMAOKA during the middle of the Edo period), 'Moritonjiki is made out of a wooden form, and Aratonjiki is served unshaped.'
According to 'Gyokkansosetsu' (miscellaneous writings by Munetake Tayasumu), there was an upper tray of a double tray, used at a wedding, in an old painting scroll illustrating a feast; although its name was unknown, it was probably Tonjiki.
According to 'Ruijuzoyosho' (a book explaining the furnishings in ceremonies and events in detail with sketches), Moritonjiki might be served with one ingredient while Aratonjiki might be served with various ingredients because of the presence of Morigashi and Mazegashi.