Question: Fukubukuro is part of what Japanese festical celebrated on January 1st sine 1873?

<P0-S0> 1st Best! <P0-S1>  (Chinese: "1st Zui Bang!" <P0-S2>  (1st最棒!) <P0-S3> , Japanese: "1st Saikō!" <P0-S4>  (1st最高! ) ) <P0-S5> , is the debut mini-album of Taiwan-based Hello! <P0-S6>  Project group Ice Creamusume. <P0-S7>  It was released on January 9, 2009 in Taiwan, with a follow up date of January 18, 2009 in Japan. <P0-S8>  The album contains songs in both Taiwanese and Japanese and contains two versions of one original song, along with five covers of famed Morning Musume songs, four sung in Taiwanese and one in Japanese. <SEP> <P1-S0>  The low prices are usually done to attract customers to shop at that store during the new year. <P1-S1>  The term is formed from Japanese "fuku" (福, meaning "good fortune" or "luck") and "fukuro" (袋, meaning "bag"). <P1-S2>  The change of "fukuro" to "bukuro" is the phenomenon known as "rendaku". <P1-S3> Fukubukuro (福袋 ) is a Japanese New Year custom in which merchants make grab bags filled with unknown random contents and sell them for a substantial discount, usually 50% or more off the list price of the items contained within. <P1-S4>  The "fuku" comes from the Japanese saying that "there is fortune in leftovers" (残り物には福がある). <P1-S5>  Popular stores' "fukubukuro" usually are snapped up quickly by eager customers, with some stores having long lines snake around city blocks hours before the store opens on New Year's Day. <P1-S6>  "Fukubukuro" are an easy way for stores to unload excess and unwanted merchandise from the previous year, due to a Japanese superstition that one must not start the New Year with unwanted trash from the previous year and start clean. <P1-S7>  Nowadays, some "fukubukuro" are pushed as a lavish New Year's event, where the contents are revealed beforehand, but this practice is criticized as just a renaming of selling things as sets. <SEP> <P2-S0>  Since 1873, the official Japanese New Year has been celebrated according to the Gregorian calendar, on January 1 of each year, New Year's Day (元日 , Ganjitsu ) . <P2-S1> The Japanese New Year (正月 , Shōgatsu ) is an annual festival with its own customs. <P2-S2>  However, the celebration of the traditional Japanese New Year is still marked on the same day as the contemporary Chinese, Korean, and Vietnamese New Years. <SEP> <P3-S0> The 4th Cavalry Regiment is a United States Army cavalry regiment, whose lineage is traced back to the mid-19th century. <P3-S1>  It was one of the most effective units of the Army against American Indians on the Texas frontier. <P3-S2>  Today, the regiment exists as separate squadrons within the U.S. Army. <P3-S3>  The 1st Squadron of the 4th Cavalry's official nickname is "Quarterhorse", which alludes to its 1/4 Cav designation. <P3-S4>  The 3rd Squadron of the 4th Cavalry's official nickname is "Raiders". <P3-S5>  Today, the "1st Squadron, 4th Cavalry", "2nd Squadron, 4th Cavalry", "4th Squadron, 4th Cavalry", and "6th Squadron, 4th Cavalry" are parts of the 1st Infantry Division, while the "3rd Squadron, 4th Cavalry" serves as part of the 25th Infantry Division. <P3-S6>  On 23 September 2009, the "4th Squadron, 4th Cavalry" officially stood up at Fort Riley, Kansas as part of the 1st "Devil" Brigade, 1st Infantry Division. <P3-S7>  On 28 March 2008, the "5th Squadron, 4th Cavalry" officially stood up at Fort Riley, Kansas as part of the 2nd "Dagger" Brigade, 1st Infantry Division. <P3-S8>  The 6th Squadron, 4th Cavalry served as part of the recently inactivated 1st Infantry Division, 3rd "Duke" Brigade, at Fort Knox, Kentucky.