To put it simply, Ayumi’s record label Avex Trax is producing a musical to, along with many other things, celebrate their 20th year anniversary.  There will be about 20 songs made by various avex artists, and “SEASONS” by Ayumi will be used.  The production is called “Kokoro no Kakera”

Avex to produce musical “Kokoro no Kakera”
Sat, June 28, 2008 (7:27pm EDT)
Music label Avex has announced that it is producing a musical this September, titled “Kokoro no Kakera.” The soundtrack is said to feature 21 songs, chosen from the company’s hits over the past two decades. This is the first time that a record company has put together a musical based on songs by several of its artists.

The musical will be performed at Tokyo’s Aoyama Theatre from September 15 to September 29.

「Feelin’ Good～It’sPARADISE～」DA PUMP
「パピヨン」島谷ひとみ [Papillion]
「LOVE2000」hitomi
「恋のつぼみ」倖田來未
「友達の詩」中村中 [Tomodachi no Uta]
「恋心」相川七瀬 [Koigokoro]
「寒い夜だから・・・」TRF [Samui Yoru Dakara]
「fragile」Every Little Thing
「SEASONS」浜崎あゆみ
「Lovers Again」EXILE
「CAN YOU CELEBRATE?」安室奈美恵
「VALENTI」BoA
「Day By Day」MEGARYU
「DEPARTURES」globe
「comea gain」m-flo
「プラネタリウム」大塚 愛 [Planetarium]
「柊」Do As Infinity [Hiiragi]
「ＤＯＷＮ　ＢＥＡＴ　ＳＴＯＭＰ」東京スカパラダイスオーケストラ
「のうぜんかつら（リプライズ）」安藤裕子 [Nouzen Katsura]
「月光花」Janne Da Arc [Gekkouchou]