昨 is a Chinese hanzi, listed here under the keyword “yesterday”. It is built from 日 (sun) and 乍 (first time). It appears as a component in 1 other character in this index.
On KumiJi Glyph Explorer, open the parts search and type “sun” + “first time”. 昨 is among the results, together with every other character containing the same shapes.
Open 昨 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.