Kagami mochi (鏡餅) double rice cakes eaten after New Year's after being used as decorations for a few days; the orange thing on them is a bitter citrus fruit called "daidai"/橙. The decoration is, of course, from the manga/anime "Kimetsu no Yaiba" (鬼滅の刃) whose main characters are demon slayers.
(For a bigger version of this picture both in color and black and white, check my "Japan Arekore" set on Flickr).