繁 is a Chinese hanzi, listed here under the keyword “complicated”. It is built from 敏 (fast) and 糸 (silk). It appears as a component in 2 other characters in this index.
On KumiJi Glyph Explorer, open the parts search and type “fast” + “silk”. 繁 is among the results, together with every other character containing the same shapes.
Open 繁 in the interactive kanji search
to expand every part down to its smallest pieces, add your own names and mnemonic stories,
or search for other characters by their parts.