According to my local friends the special meaning of this season is to have a fresh new start for the year with the past 105 sins being redeemed. People go to temples to pray and pay their respects in order to be cleansed from the sins of the passing year.
Enough food is prepared to last for 4 days so that no cooking is required during the celebration. Previously it used to be a big effort to prepare all the different dishes beforehand but these days people buy them from stores. Prices can vary from several thousands to hundreds of thousands yens.