The Japanese driver improved on each of his three passes through the 4.12km Ruuhimäki test, progressing from 2min 16.3sec to 2min 12.5sec before stopping the clocks at 2min 11.7sec on his final run.
That left Katsuta 0.9sec clear of both Adrien Fourmaux and Oliver Solberg, who posted identical times of 2min 12.6sec.
Fourmaux also found speed on every pass aboard his Hyundai i20 N Rally1, while Solberg shaved 3.3sec from his opening effort as both drivers underlined their potential ahead of the rally’s opening Harju super special on Thursday evening.
Championship leader Elfyn Evans was fourth-fastest, 1.7sec behind his Toyota team-mate, with Estonia winner Sami Pajari a further two-tenths back in fifth on his home event.
Thierry Neuville placed sixth for Hyundai, just 0.1sec ahead of M-Sport Ford’s Jon Armstrong. Esapekka Lappi and Josh McErlean shared the eighth-fastest time, both recording 2min 14.0sec, while Mārtiņš Sesks completed the top 10.
Sébastien Ogier and Julien Ingrassia began their one-off reunion with the 11th-fastest time. The Toyota duo were quickest on their opening pass in 2min 14.7sec but did not improve thereafter, ending 3.0sec adrift of Katsuta.
The competitive action begins on Thursday evening with two passes of the mixed-surface Harju super special in central Jyväskylä.