adverb, suffix
just; exactly; precisely; on the dot
Used with times, amounts of money, and other numerical expressions to mean 'exactly' or 'right on'. As a suffix, it attaches directly to numbers.
会議は3時ジャストに始まった。
The meeting started at exactly 3 o'clock.
合計は1万円ジャストだった。
The total was exactly 10,000 yen.