on the occasion of, at the time of
Noun / Verb (Dictionary Form) +
A compound particle used in formal Japanese to indicate doing something or having done something on the occasion of, at the time of, or just prior to a significant event.
Noun +
Attach directly to a noun representing an event, ceremony, or milestone to mean on the occasion of that event.
卒業
On the occasion of graduation, I gave a present to the teacher.
開会に
Prior to the opening of the meeting, the company president gave a greeting.
Verb (Dictionary Form) +
Attach to a verb in its dictionary form (informal non-past) to express doing something before or on the occasion of an important action.
新しい車を買う
Before buying a new car, I checked various stores.
事業を始める
On the occasion of starting the business, I borrowed money from the bank.
This grammar point is highly formal and is typically reserved for special occasions, ceremonies, speeches, or formal announcements. It should not be used for everyday, casual events like going to the supermarket or eating dinner. The version ending in に