Ken Hirai's steady, competent falsetto, good looks and, most importantly, predilection for classic R&B and soul, which he mixes with jazz, funk, and hip-hop, made him a top-league feature on the Japanese scene and throughout East Asia, with the total amount of CDs he's sold being close to 14m. His career began in the early ‘90s: in 1993, Hirai, still a student, won the audition at Sony and got a deal with the label. He started big -- his first two singles, Precious Junk and Katahou Zutsu no Earphone (both 1995), were used in TV dramas, -- but the sales of his two albums, Un-Balanced (1995) and Stare At (1996), were modest, and so Hirai proceeded with caution, dropping only two singles from 1997 to 1999. He returned in glory in 2000, when his third studio album The Changing Same sold 1.26m copies (the single Rakuen (2000) added 500,000 more), getting him gigs at MTV Summer Summit in Taiwan and even the R&B Mecca of Apollo Theater in New York, him being the first Japanese performer to play the venue.

The single Kiss of Life (2001) was used in the successful TV series Love Revolution, and the album Gaining through Losing sold 1.5m copies in all of Asia. Hirai also wooed the club crowd with his remix CD Kh re-mixed up 1 (2001), and continued to advance internationally in 2002-2003, appearing in Los Angeles with Babyface (he also wrote for Hirai the song "Missin' You: It Will Break My Heart"), releasing "Ooki na Furudokei" (2002), the Japanese cover of "My Grandfather's Clock", which became a smash hit (772,000 copies sold), sharing the stage with Lauryn Hill at the FIFA World Cup concert and playing an MTV Unplugged in New York in 2003. He also had a prolific streak in the studio, releasing Life Is… and Ken's Bar in 2003 and Sentimental Lovers in 2004 (Ken's Bar consisted of covers of classic jazz and blues numbers). Sentimental Lovers sold 1.66m copies and spawned the super-hit Hitomi wo Tojite, which became #1 on the Japanese yearly singles chart. However, that was followed by an extensive break: Hirai only released two singles in 2005 and 2006, although his collection Utabaka (November 2005) sold 2.1m copies, becoming the top selling album of 2006. Hirai's returned to active mode in 2007, although his singles Elegy and Kimi no Suki na Toko, unsurprisingly, didn't chart as high as their predecessors, even if still managing to shift about 100,000 units each. In 2008 Hirai released his first double A-side Canvas / Kimi wa Su.te.ki, of which Canvas was featured in the live action adaptation of the hit manga series Honey and Clover. The album Fakin' Pop, his first in four years, came out in 2008, reaching #2 and selling 330,000 copies. ~ Alexey Eremenko, All Music Guide