Osech-ryori are special side dishes eaten on the first three days of the new year.. Tiered lacque boxes are abundantly loaded with multi-hued side diehses, grilled or boiled dishes and vinegared dishes.. It appears that present-day osechi-ryori was developed with the parituclar practice of keeping it as is for a while, because it is splendid to look at, and also out of consideeration for reducing housewives' work for three days.. There are some regional differences but osechi contents are essentially fixed.
Those contents are respectively charged with wishes; for example,, sea bream(tai) is "auspicious"(mede-tai), herring roe (kazu no ko) indicates "the prosperity for ones descendants", and sea tangle roll (kobu maki)means "happiness"(yoro-kobu)
by the book "Traditional Japanese Culture & Modern
BTW, I COOKED SEVERAL ,,, NOT ALL ,,LOL.