The 72-season calendar (shichijuniko) was adopted in Japan from China during the Edo period (it was published in Japanese form in 1685 by Shibukawa Shunkai); the shun concept as a culinary value is documented from the Heian period in court poetry and cooking manuals; the modern kaiseki calendar preserves this ancient seasonal framework
The concept of shun (旬 — 'season' or 'peak moment') is the most fundamental organising principle of Japanese cuisine — the belief that each ingredient has a brief window of peak flavour, nutrition, and spiritual vitality that defines when it should be eaten. Shun is not just freshness — it is specifically the moment before peak when flavour is most concentrated and dynamic. The shun calendar divides into 72 micro-seasons (sekki) based on traditional lunar-solar calendar, with specific ingredients peaking in each 5-day period. Examples: bonito (katsuo) has two shuns — hatsu-gatsuo (first bonito, late spring) and modori-gatsuo (returning bonito, autumn); Kyoto eggplant peaks for 2 weeks in late August; matsutake mushroom's shun is a single October fortnight; iwashi (sardine) in summer when fat content is highest. The Japanese concept of hatsumono (first-of-the-season produce) carries premium pricing: the first strawberry, the first bonito, the first matsutake are priced dramatically above the seasonal average because their rarity signals the beginning of a sensory experience. Eating hatsumono was considered health-giving in the Edo period — the concentrated vitality of first-season produce transferred to the eater.
The flavour case for shun is physiological: strawberry sugar content peaks for 3–5 days at the point of maximum ripeness; bonito fat content peaks in autumn when the fish has been feeding in warm northern waters; matsutake's aromatic compounds are at maximum concentration in the first cool days of autumn before heavy rains dilute them; eating at shun is not aesthetic convention but flavour optimisation
Shun is about peak moment, not merely availability; 72 micro-seasons govern the ingredient calendar more precisely than 4 macro-seasons; hatsumono (first of season) commands premium; cooking methods are calibrated to the seasonal moment — spring ingredients need lighter treatments, autumn ingredients can take depth; the shun ingredient defines the entire meal's character in kaiseki.
The professional kaiseki chef's shun awareness: visit the market daily and design the menu based on what is exhibiting peak condition that morning, not what was planned; the shun test for fish: bright eyes, firm flesh, tight scales, clean gills, no fishy smell — all indicators of peak condition; for vegetables: maximum weight for size (water content), tight skins, bright colour — all indicate peak cellular hydration and freshness; shun awareness is a learnable skill — attend farmers markets, taste the same ingredient repeatedly through its season.
Confusing 'available' with 'shun' — global supply chains make most ingredients technically available year-round, but shun refers specifically to optimal-peak local production; treating shun as a marketing concept rather than an actual flavour reality — out-of-season tomatoes and in-season tomatoes are genuinely different foods.
Tsuji, Shizuo — Japanese Cooking: A Simple Art; Murata, Yoshihiro — Kaiseki