はこせこ

Etymology
Compound of.

Although the derivation of the seko element is left unexplained in Japanese resources referenced to date,     this could be a compound of  +, as suggested by the alternative kanji spelling , and presumably indicating the shape of the hakoseko itself. Alternatively, it might be from the slang term,   itself possibly a similar compound.

Noun

 * 1)   a women's billfold or wallet, often ornately decorated and kept in the ; over time, this developed into something like a small boxy purse, though still kept in the futokoro
 * 2)   a decorative such billfold or purse only used for certain special occasions requiring traditional dress, particularly the  ceremony for children aged seven, five, and three