Cherry on top

tʃaɪniːzle̞tə tʃaɪniːzle̞tə tʃaɪniːzle̞tə tʃaɪniːzle̞tə keɪ aɪ ɛn dʒeɪ əʊmakɹɒn tiː iː ɛn keɪ eɪ

In Japanese 錦上添花 (kinjō tenka)

This idiom means 'to add flowers to the brocade' and is used similarly to 'cherry on top'.