Japan — Shinto and Buddhist New Year tradition, documented from Heian period
Kagami-mochi (鏡餅, mirror rice cake) is the round, stacked New Year's decoration placed on the tokonoma alcove or family altar from December 28 until January 11 (Kagami Biraki, mirror opening). The two-tiered stacked round mochi discs — a larger lower disc topped by a smaller one, crowned with a daidai bitter orange — represent the moon, the sun, and generational continuity. The ritual production of kagami-mochi involves pounding (mochi-tsuki) the stickiest short-grain glutinous rice (mochigome) in a large wooden mortar (usu) with a heavy wooden mallet (kine) — a community and family ritual performed on December 28 (the 29th is considered unlucky for pounding as 'ku' means suffering; the 31st is too rushed, a one-night decoration). Traditional mochi-tsuki involves alternating between pounding and folding: one person pounds while another quickly folds the paste between blows — extreme coordination required. After the pounding reaches the desired sticky, smooth consistency, the kagami-mochi are formed by hand into rounds while still warm, placed on clean washi paper. On Kagami Biraki (January 11), the hardened mochi are cracked open (never cut — cutting is samurai terminology; the hammer crack is the correct approach) and the pieces are boiled in ozoni soup or toasted as yakimochi, eaten to receive the New Year's luck stored within.
Neutral, subtly sweet glutinous rice — the flavour is carried by condiments: kinako, kuromitsu, soy sauce, or the rich dashi of ozoni soup
{"Mochigome (glutinous rice) must be soaked 12–16 hours before steaming and pounding — insufficient soak produces grainy, uneven mochi","Alternating pound-and-fold between two people is the correct technique — the fold incorporates air and smooths the texture","Kagami-mochi should be cracked (not cut) on Kagami Biraki — the word 'kiru' (to cut) is avoided at New Year as it implies severing luck","The daidai (bitter orange) on top represents 'from generation to generation' (代々, daidai) — a pun linking the fruit to family continuity","December 28 is the traditional mochi-tsuki day — the 29th (ku, suffering) and 31st (rushed) are avoided by custom"}
{"Home mochi-tsuki uses a stand mixer with a dough hook if a traditional usu is unavailable — process the steamed mochigome on low speed for 20–30 minutes until fully glutinous","Freshly pounded mochi should be eaten with kinako and kuromitsu (black sugar syrup) or wrapped in nori with soy sauce (isobemaki) while still soft and warm","Harden kagami-mochi naturally at room temperature rather than refrigerating — refrigeration makes the mochi crack unevenly and affects the texture when recooked","For ozoni on Kagami Biraki: the mochi pieces are briefly toasted in a toaster oven before adding to the clear dashi soup — the charred exterior holds up in the broth"}
{"Using regular short-grain rice instead of mochigome — regular rice lacks the amylopectin content needed for the glutinous stretch","Cutting hardened kagami-mochi with a knife — use a hammer or wooden mallet to crack; this is a cultural distinction, not merely symbolic"}
Japanese New Year Customs documentation; Folk tradition surveys (Nihon Minzoku Daijiten)