Shōgatsu is very important event in Japan and that was originally thought to the ceremony of welcoming Toshigami[年神 / 歳神（としがみ）]. Toshigami is a deity of Shinto who comes to each house on Shōgatsu and brings good luck and fertility of the year. Toshigami was important for Japanese people because Japan was an agricultural country. Shōgatsu-kazari are decorations for welcoming Toshigami.
The representative Shōgatsu-kazari are as follows:
Kadomatsu is a decoration made of pine, bamboo, etc. (or only pine, 'Matstu' means 'pine' in Japanese) and that is displayed at the entrance of house gate. Kadomatsu is an object to which the Toshigami is drawn and is a landmark for Toshigami.
The period of displaying Kadomatsu is called 'Matsunouchi[松の内（まつのうち）]' Matsunouchi is from January 1st to 7th in the eastern region or 15th in the western region. But Kadomatsu and other Shōgatsu-kazari is usually displayed from December because of welcoming Toshigami.
- Shimenawa[注連縄（しめなわ）] and Shimekazari[注連飾り（しめかざり）]
Shimenawa is a sacred straw rope and Shimekazari is a decoration made of Shimenawa with the fruit of Daidai[橙（だいだい）](a kind of citrus), leaves of Yuzuriha[ユズリハ] (Daphniphyllum macropodum) and Urajiro[ウラジロ](a kind of ferns), etc.
Shimenawa and Shimekazari is a barrier separating the purified place from the secular society and that is displayed at the door. And they prevent harm and evil from coming into the house. Daidai and Yuzuriha symbolizes a wish for the prosperity of descendants and Urajiro symbolizes incorruption.
- Kagami-mochi[鏡餅（かがみもち）](rice cake for display)
Kagami-mochi is an offering for Toshigami. Kagami means mirror in Japanese and Mochi[餅（もち）] is a rice cake.
Kagami-mochi is a decoration of ancient mirror shaped Mochi and that is generally displayed with the fruit of Daidai, leaves of Yuzuriha, Konbu[昆布（こんぶ）](kelp), etc. Konbu is displayed because it is associated with the word 'Yorokobu[喜ぶ（よろこぶ）](joy)'.
That is taken away on January 11th(or 20th or some day, it depends on the region.) and the Mochi is eaten. That event is called 'Kagami-biaki[鏡開き（かがみびらき）]'.
- Hamaya[破魔矢（はまや）] and Hagoita[羽子板（はごいた）]
Hamaya is an arrow-shaped charm for expelling evil. That can be purchased at the shrine and temple.
Hagoita is originally a wooden paddle for Hanetsuki[羽根付き（はねつき）] which is a game like a badminton and which is played at Shōgatsu. That has also come to be a charm against evil. And Hagoita for display is decorated and that is different from Hagoita for Hanetsuki.
Hamaya and Hagoita is displayed especially in the family with new baby. Hamaya is for boys and Hagoita is for girls.
Paper Kadomatsu: That is mainly distributed by municipalities and is stuck on the gate instead of Kadomatsu.