Since its release, the album brought Hamasaki a myriad of accolades and award nominations with a conga line of successful recognition throughout Eastern and Western publications.

But if it's a best-of album, it might be an opportunity for people who weren't interested in her before to listen to her, so I wanted to sing her old songs with her current vocals.

[4] Avex had contacted Hamasaki one day, and stated that they intended to release the album on a specific date unbeknownst to her.

The singles released in the first year of the debut were still very much an exploration, and rather than saying that they had to be this one in particular, I thought that the message we wanted to convey would not change that much no matter which one we included.

"[3] The date announcement was a widely controversial topic throughout Japanese and Western media, which claimed the two singers were "rivals" on both personal and professional circumstances.

[8][9][10] Hamasaki denied the claims, but decided to take more control of her future material and asserted that she didn't want to be marketed as a "product" by Avex.

[13][14] Also, among the singles released in the selected years, the songs “Poker Face,” “You,” “For My Dear...,” “Whatever,” “Love (Since 1999),” “Monochrome,” “Too Late," "Kanariya” and “Audience” were not included in the track list.

[12] Knowing that the material was still insufficient, Hamasaki reluctantly re-recorded three tracks; "Trust," "Depend on You" and the non-single "A Song for ××."

[12] Hamasaki also selected the non-single "Who..." to be included on the album; "Who..." excluded the hidden track "Kanariya," which appeared on Loveppears.

[12] The cardboard sleeve of the album was photographed by Keita Haginiwa, whilst the booklet was designed by Shigeru Kasai from RICE.

Hamasaki stated in an interview that she chose for the album cover to be monochromatic because she wanted to make a simple piece that would never go out of style, that would never feel out of date.

Tomoyoki stated that, whilst her initial presentation as an artist was described as "idle", he labelled the album's material as "excellent".

[30] Hamasaki's album sales reached an excessive ¥12 billion (approximately $77,284,200 US dollars) by the end of the year, which hugely effected the stock prices of the record company.

[33] Hamasaki became the spokeswoman for the KDDI Corporation subsidiary company Tu-Ka, which manufactured 2G PDC cellular operator's in three metropolitan areas (Tokyo, Nagoya, and Osaka).

[5] Hamasaki had been hospitalized a few times for consultations, but a doctor confirmed that continuing her to pursue music would result in permanent hearing loss.

[5] During some stage rehearsals at Tokyo Dome, Hamasaki became sick due to her hearing problems and could not finish the performances.

[36] Despite the setback, Hamasaki stated that she wished to continue singing, and that she would "not give up" on her fans and that "as a professional", she wanted to "deliver the best performance for everyone".

[40][41] Through an exclusive deal with Sony, they released a limited edition PlayStation 2 musical video game entitled Visual Mix: Ayumi Hamasaki Dome Tour 2001 (2001).

[42] The video game is split into three sections; the visual mix (where the player uses the controller to change and direct the respective music videos and concert tour, alongside special effects editing), the Ayu-Mi-x studio (where the player can create and edit music through her songs "Unite!"

Many critics commended the song's composition, lyrical content, and highlighted the track as one of Hamasaki's best singles in her career.

[46] "M" was successful in Japan, peaking at number one on the Japanese Oricon Singles Chart by selling over 500,000 units in its first week of sales.

[51] The accompanying music video for the single was shot in Tokyo by Wataru Takeishi;[52] it features Hamasaki inside a church, with scenes of her wearing a wedding dress and singing with her backup band in the rain.

[59] With additional sales from digital purchases, A Best has sold over five million units in Japan, making this Hamasaki's best selling effort as of today.

[64] Alexey Eremenko from AllMusic stated that, whilst the album was a success, he noted that A Best was the moment that there was the "serious friction" between Hamasaki and her label; this was one of the first publicized rifts between the parties in Japan music history.

It was issued on her compilation albums; A Ballads (2003),[65] the A Best 2 (2007) black and white editions,[66][67] A Complete: All Singles (2008),[68] A Summer Best (2012)[69] and M(a)de in Japan (2016) where it's put in brackets.

[74] In retrospect of the album, Hamasaki had been interviewed in 2004 for the Nippon TV special documentary Light and Shadow: Despair and Decision at Age 25.

[5] Hamasaki denied claims of retirement from the music industry, but threatened her position within Avex by wanting to separate from them.

[77][78] On one of Hamasaki's posts on her website, several Japanese public figures such as ice skater Mao Asada, Japanese model and actress Riisa Naka, music writer Mihi Fujii, and sociologist Noritoshi Furuichi took appreciation and retrospect in the collection and commended Hamasaki's longevity in the music industry.

[80] The DVD and Blu-ray bundles are housed inside a special box packaging, and features the music videos to ten of the tracks.

[81] On its opening day release, A Best: 15th Anniversary Edition debuted at number nine on the Oricon Daily Albums Chart with just over 2,000 units sold.