Shoji Yokouchi (横内章次, Yokouchi Shoji in Japanese order) was born on November 9, 1933, in Dalian, the port city at the southern tip of Manchuria, then under Japanese administration. He was a Japanese national, and everything documented about his working life took place in Japan. According to the Japanese Wikipedia article on his younger brother, the actor Tadashi Yokouchi, their father was a violinist who owned a dance hall in Dalian and led its band, so music came with the household. Tadashi (born 1941, also in Dalian) is best known for playing the magistrate Ooka Tadasuke on the long-running television series Abarenbo Shogun; another brother, Hiroshi Yokouchi, was a guitarist, and Japanese Wikipedia also lists the guitarist Hiroshi Okawa among his brothers. They are separate people with careers of their own, and credits under their names are not Shoji's.

After graduating from Dalian Commercial High School and the end of the war he returned to Kyushu, where he played for American military audiences at the camps in Kokura. Japanese Wikipedia says he went on to work with the bandleaders Hiroshi Watanabe, Jun Yoshiya and Seiji Hiraoka before forming a group of his own. The earliest record on Discogs that credits him is Seiji Hiraoka Plays MJQ Favorites (Toshiba, 1961), a vibraphone-led set of Modern Jazz Quartet repertoire on which he plays guitar with Hiraoka's quintet on three tracks. In 1964 he was the guitarist in the Modern Jazz All Stars' Modern Jazz In Tokyo (Polydor SLJM 1118), a hard-bop and soul-jazz date arranged by the pianist Norio Maeda, with the tenor saxophonist Akira Miyazawa, the drummer Takeshi Inomata, the alto saxophonist Shigeo Suzuki, the trumpeter Akira Nakano and the bassist Tatsuro Takimoto, playing "Moanin'", "Work Song", "Sister Sadie" and "Take Five" among others.

The larger part of his output in the 1960s was not jazz in that sense. Japanese Wikipedia says he made leader albums for King, Victor, Polydor and Nippon Columbia, and that he played guitar and wrote arrangements for the foreign-music divisions of the labels and for group-sounds bands. His Polydor LPs of 1965 with the Beat Beat Beat, among them Let's Go Guitar Beat and Guitar, Go! Go! Go!, are surf and beat-guitar records, and Discogs files them under rock. In 1967 Toshiba issued Top Stars in Guitar (TP-8034), a set of standards with Shungo Sawada and the Golden Sounds on which Yokouchi arranged six tracks, Masao Yagi three and Norio Maeda three. Toshiba then signed him exclusively as "Mr. Guitar", and the Mr. Guitar series of instrumental LPs, many of them with the Blue Dreamers, ran from 1968 into the 1970s alongside a Golden Guitar series with a large orchestra. Japanese Wikipedia adds that he appeared as a guitar star and the heroine's brother in the 1967 Nikkatsu film Yuhi ga naite iru with The Spiders, that he composed "Yuhi ga shizumu", which The Ventures recorded as "Slow Sundown" on their 1967 Liberty LP Pops In Japan (he is credited as composer, lyricist and arranger on The Four Dimes' Capitol single of the song, CR-1630, from January 1967), and that, writing as Hal Watkins, he composed "Summer Creation" for the singer Joan Shepard, which won a gold disc.

His jazz records cluster in the 1970s and early 1980s, many of them for the audiophile label Three Blind Mice and its producer Takeshi Fujii. In 1970 he was the guitarist on Jimmy & Teddy (Toshiba TP-7490), the drummer Jimmy Takeuchi's trio session with the American pianist Teddy Wilson and Masanaga Harada on bass; Takeuchi, Wilson and Yokouchi made a second record, Swing (Express, 1978), with the clarinetist Shoji Suzuki. He played guitar on the singer Mari Nakamoto's debut Unforgettable! (1973), and Japanese accounts of her early career say he and the pianist Yasuro Osawa were her accompanists at the Akasaka club VIPA ROOM. In 1974 Little Girl Blue billed her with the Shoji Yokouchi Trio and the organist Yuri Tashiro, and in 1977 Mari put her in front of his trio and sextet. His own Satin Doll (Toshiba, 1975) was a trio date with the bassist Kunimitsu Inaba and the drummer Jimmy Takeuchi. He arranged Nakamoto's big-band album That Old Feeling (Toshiba, recorded in August 1976), played guitar and arranged her Nice Feeling (Victor, 1977), and did the same on Love Touch (Victor, 1978). On March 17, 1976, at Epicurus Studio in Tokyo, he recorded Blonde On The Rocks (Three Blind Mice TBM-65), a quartet date for two electric guitars with Toru Konishi, the bassist Masanaga Harada and the drummer Hajime Ishimatsu. The singer Toshio Oida's It Was A Very Good Year (TBM-64) was recorded at the same studio on March 17 and 18, with Yokouchi as both guitarist and arranger. He also played on the bassist Isoo Fukui's Sunrise/Sunset (TBM-78, 1976).

1977 was his busiest year on record. Lady Bird (Audio Lab ALJ-1054), recorded on March 8 with the pianist Kazuo Yashiro, the bassist Osamu Kawakami and Ishimatsu, is one of the albums Japanese Wikipedia names among his jazz work; the obi on the Japanese LP announces the Swing Journal Jazz Disc Award for best recording and bills the interplay of Yokouchi and Yashiro. In April he and Nakamoto recorded Mari with Inaba, Ishimatsu and, on four tracks, the tenor saxophonist Konosuke Saijo, the trumpeter Tetsuo Fushimi and the vibraphonist Kazuhiro Matsuishi. Boiling Point (Toshiba LF-95009), billed to a group of that name, has him as guitarist and arranger with Inaba, Saijo, Matsuishi and the drummer Moto Nomura, and Nakamoto singing two tracks. In June, at Epicurus Studio again, he played guitar and wrote the arrangements for the singer Ayako Hosokawa's debut To Mr. Wonderful (TBM-3008), with Tsuyoshi Yamamoto on piano, Fukui on bass, Tetsujiro Obara on drums and Saijo on tenor, and the same year he arranged and conducted the strings on Yamamoto's Star Dust (TBM 3009). He was the guitarist on Takeshi Inomata's duet record The Dialogue (Audio Lab ALJ-1059), which gives each track to the drums and one other instrument, and he made the classical-arrangement album Sabre Dance with the violinist Shigeru Toyama.

Greensleeves (Three Blind Mice TBM-5011) followed in September 1978, recorded on the 6th and 8th: his trio with Inaba and Ishimatsu, joined by Yuri Tashiro on Hammond organ, with Yokouchi on electric, folk and gut-string guitar. Impex Records reissued it on 180-gram vinyl in a limited edition of 3,000 copies, and audiophile reviewers wrote about the reissue in 2018. In 1980 he arranged and played on Aranjuez (RCA RVJ-6086) by The Super Guitar Fusion, a four-guitar album with Sadanori Nakamure, Toru Konishi and Takao Naoi, with Inaba and Ishimatsu; he also arranged and conducted the harpist Stephanie Pelz's Finger Magic that year. In 1984 he played guitar on the vocalist Martha Miyake's Yesterday / More (Philips S-7116), billed to her with the Shoji Yokouchi Quartet, and in 1986 he played on three tracks of My Friends (CBS/Sony), a Kazuo Yashiro Trio session with the tenor saxophonist Hidehiko Matsumoto and the vibraphonist Ichiro Masuda.

Alongside the records under his own name he was one of the most heavily credited arrangers and session guitarists of his generation in Japan. He arranged Chiyo Okumura's 1971 single "Shuchakueki" (Toshiba TP-2593), and Japanese Wikipedia credits him with orchestrations for the singers Peggy Hayama, Martha Miyake, Toshio Oida, Yoko Kishi, Yoichi Sugawara and the Duke Aces, ballroom-dance orchestras and television commercials.

Yokouchi is a borderline case for a jazz catalogue, and the plain version is this. A large share of his output is easy listening and pop: the Mr. Guitar and Golden Guitar series, the 1965 beat-guitar LPs, soundtrack and "screen music" albums, quadraphonic showcase records, and a long run of arranging for kayokyoku singers. Discogs files much of the leader catalogue under Jazz with an Easy Listening style tag, and the rest under Rock or Pop. The jazz is a smaller core within it, roughly fifteen albums between 1961 and 1986, most of them on Three Blind Mice, Audio Lab and Toshiba. That core is real: Japanese Wikipedia calls him a representative guitarist of Showa-era jazz, and it names Top Stars in Guitar, Satin Doll, Django, Aranjuez, Lady Bird, Sabre Dance, Boiling Point, Greensleeves, Blonde On The Rocks and Nakamoto's Mari as his serious jazz-guitar work. He is profiled here for that core and with the rest in view.

As a player he combined jazz technique with a direct, singing line. Japanese Wikipedia describes a style that wove in the technique he had built in jazz while singing out straight melodies strongly and with feeling, with a tone of its own. The records show the range: Modern Jazz Quartet repertoire in 1961, hard bop in 1964, Latin-flavoured instrumentals under Mr. Guitar, ballads and standards in the trio format, and electric two-guitar and four-guitar fusion in the late 1970s. On Greensleeves Discogs credits him on electric, folk and gut-string guitar, and The Audio Beat's reviewer found him more convincing on acoustic, calling his strength his command of the guitar rather than composition. The Audio Beatnik described the album as mellower than the other Three Blind Mice titles he knew and praised the Hammond organ playing of Yuri Tashiro.