The shock move follows another disastrous result for Alesi, the son of ex-Formula 1 driver Jean, in last weekend's Sugo race as he spun on the opening lap and was collected by Yuhi Sekiguchi, eliminating both drivers.
Alesi had gone into the 2023 campaign, his second as a full-timer at TOM'S, under big pressure as the team elected to keep him in place after trialling two-time race winner Sasahara in last year's post-season Suzuka test.
TOM'S director Jun Yamada told Autosport that commercial factors had been the main consideration in allowing Alesi to race on for another year despite the Frenchman scoring points only once in 2022.
After failing to finish either race in the Fuji opener, Alesi registered his first points of the season in April's Suzuka race in eighth, but was a disappointing 13th in the following race at Autopolis before his early Sugo DNF.
Alesi had told Autosport after his collision with Sekiguchi that he had hoped to use this week's two-day test at Fuji as a chance for a reset.
However, on Tuesday, the bombshell news arrived that his seat will be taken over by Sasahara, who had taken an unofficial reserve position within the Toyota stable after losing out on a TOM'S drive this year.
Source: Autosport