瑠 is a Japanese kanji written with 14 strokes, listed here under the keyword “marine blue”. It is built from 王 (king) and 留 (detain). In Remembering the Kanji by James W. Heisig it is frame 1528.
On KumiJi Glyph Explorer, open the parts search and type “king” + “detain”. 瑠 is among the results, together with every other character containing the same shapes.
Open 瑠 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.