Anai is an office worker and a supporting character in the 1-minute TBS Television shorts. He made his official premiere in the Netflix Original series in the episode titled "The New Hire Named Anai" as an antagonist for the first half of Season 2.
Anai is a graduate accountant who works at the same firm as Retsuko and is left in her care for training.
(Source: Aggretsuko Wiki)