Katsumi Horii (堀井勝美) is a Tokyo-born keyboardist, composer, arranger and producer who works in two public lives that rarely meet. In one he is the leader of the Horii Katsumi Project, the studio fusion band he ran from 1987 to 1998, which put some of Tokyo's best session players into glossy, melodic instrumental albums wrapped in illustrations by Eizin Suzuki (鈴木英人). In the other he is a working composer for Japanese television, film and animation, with six Doraemon feature films and the opening theme of NHK's children's programme Okaasan to Issho among his credits.

He was born in Tokyo on November 15, 1955, and graduated from the composition course at Tokyo College of Music, where he studied under Shigeaki Saegusa and Teizo Matsumura. After graduating he began work as a composer, and from 1989 he taught in the college's newly founded film and broadcast music course, later renamed the Music Media course, where he became chief professor and is now a visiting professor. Japanese Wikipedia names the musician Akihito Tokunaga among the people he went on to teach.

The Project began on record with Hot Is Cool (Air Records RAL-8845), released on March 21, 1987, with Horii credited as composer, arranger, producer and keyboardist. The band around him was Yoshihiro Naruse on bass, Hiroyuki Namba and Nobuo Kurata on keyboards, Hirokuni Korekata on guitar, Susumu Kazuhara on flugelhorn, Hidefumi Toki on saxophone and Masato Kawase on percussion. Avenue of Entertainment followed in September of the same year, and twelve Project albums were out by 1998, one of them a ballad collection, along with a single. Naruse and Toki are credited on ten of the Discogs releases each, which makes them the nearest thing to a fixed front line.

Around that core the guest list kept widening. Toshiyuki Honda on saxophone and Minoru Mukaiya on keyboards are credited on Ocean Drive (1988) and Front and Rear (1989), where Larry Coryell also plays acoustic guitar. Masato Honda plays saxophone on Sky Cruisin' (1991). Lovers (1993) brought in Grover Washington Jr. and Bob Mintzer on saxophone and Steve Khan on guitar, and Blue Waters (1998), the last Project album, has Omar Hakim on drums, Mark Egan on bass, Hiram Bullock on guitar and Philippe Saisse on keyboards. Keyboardist Soichi Noriki, guitarist Jun Kajiwara and drummer Masaharu Ishikawa appear across the discography as well.

The albums also carry a running joke. Every one of the twelve Project albums on Discogs has a track titled "Alone At Last" with a different subtitle, and on eight of them it is the closing track: "Alone, At Last" on Hot Is Cool, "Alone, at Last Again" on Avenue of Entertainment, "Alone At Last, And Then" on Ocean Drive, "Humm... Alone At Last" on Front and Rear, "Alone At Last, For This Summer" on Summer's, "Alone At Last, Behind The Seventh Wind" on Sky Cruisin', "Alone At Last, In The Misty Rain" on Lovers and "I Wish You Were Here ~ Alone At Last" on Sunday Brunch.

Much of the Project's music was written to work on air. "Cruising Boy," from Ocean Drive, came out as his only single in 1988 and was the Lion shampoo commercial theme. "An Empty Suitcase" on Front and Rear was a Denso car air-conditioning commercial. A song titled "Wave An Empty Suitcase" is one of two he composed and arranged for Hideki Saijo's album Golden Earrings (1989). "Astral Wonderland" was a TV Asahi daytime-show theme, "Green" from Summer's the theme of the NHK morning drama Rinrinto (1990), and "Skyscraper" from Lovers the theme of WOWOW's world boxing broadcasts. Two albums were drama soundtracks: Charming (1992, issued under his own name) for Kirei ni Naritai and I Believe (1995) for the NHK morning drama Hashiranka!. He appeared in episode 74 of that series in a non-speaking cameo as a record producer.

In 1999 he took over the music for the Doraemon feature films from Shunsuke Kikuchi, who stayed on for the television series and short films. His six films run from Nobita no Uchu Hyoryuki (のび太の宇宙漂流記, 1999, co-credited with Senri Oe) to Nobita no Wan-Nyan Jikuden (のび太のワンニャン時空伝, 2004), and he continued until the programme's renewal in 2005. He wrote the opening theme of Okaasan to Issho from April 1999 to March 2009 and all the incidental music for its puppet show Gu-Choco Lanteen. His anime scores include Mushrambo (2000), Rockman.EXE and the fifth GeGeGe no Kitaro series. He also wrote a column, "Offside na Hibi," for the music magazine ADLIB until the magazine's final issue in May 2010.

The Project albums were out of print for years, then found a new audience as the city pop boom carried Japanese fusion overseas. Horii supervised new remasters of ten of them, five titles on January 25, 2023 and five more on March 8, 2023, sold through Tower Records and Sony Music Shop, and a limited clear blue vinyl edition of Hot Is Cool followed in 2024. On October 29, 2025, ten of the albums reached Apple Music, Spotify and the other streaming services. He is 70 and is listed on the Tokyo College of Music faculty as a visiting professor.

Horii's own records belong to the polished, studio-built side of Japanese fusion in the late 1980s and 1990s: melodic instrumental pieces for a rhythm section, a saxophone, flugelhorn or guitar lead, layers of synthesizer and programmed percussion, and short themes written to be remembered after one hearing. Discogs files every Project album under Jazz, tagged Fusion, with Jazz-Funk, Jazz-Rock or Smooth Jazz added on some of them, and Japanese Wikipedia gives his genre as fusion.

On the albums where Discogs itemises the credits, he is credited as composer, arranger and producer, with the session players listed separately, and the personnel can move from Japan's studio regulars to Larry Coryell, Grover Washington Jr. or Omar Hakim within a few releases. The jazz content lives in the soloists, most often Hidefumi Toki's saxophone, and in the harmony and groove under them; the tunes themselves are compact and hook-led rather than open-ended.

The balance of his working life is commissioned music for screen and stage, and listeners in the jazz world know him almost entirely through the Project records. They were built for radio and television use as much as for the listening room, and Japanese Wikipedia notes that broadcasters still draw on them often.