Where the shape comes from
A cord or thread bent back on itself, tied off — one account behind its use for the sixth of the ten heavenly stems and, by an easy extension, for the self: a life is a thread that turns back on itself, definite and bounded. It gives 自己, oneself, and lends its shape to 记, to record, and 纪, discipline or an era, both built around speech or thread put in order.
汉字 filed under 己
No published character on HSK Guide is filed under this radical yet. 汉字库.