にTime-point marker
に marks the specific time at which an action or event happens.
Locating an event in time
Think of the time expression as a point on a schedule or calendar. The particle follows that point and tells you when the action or event occurs.
会議は午前十時に始まります。
The meeting starts at 10 a.m.
AnalyzeDates and occasions
A calendar date or an occasion such as a birthday or vacation can also serve as the event time.
Weekdays
月曜日に試験があります。
There is a test on Monday.
Analyzeえっ、月曜日、試験がありますか。
What, there is a test on Monday?
AnalyzeBoth speakers use the weekday naturally. The first includes に, while the second omits it.
Asking for a specific time
明日の飛行機は何時に出ますか。
What time does tomorrow's flight leave?
Analyze明日、九時に出ます。
It leaves tomorrow at nine.
Analyze明日 appears without the particle, while the precise clock time takes it.
A time point is not a rate or deadline
Here, に identifies when one event happens. When a time period is the basis for a recurring rate, the particle has a different use. The form までに instead sets a deadline: something must happen by that time, not necessarily at that exact time.
More examples
毎朝六時半に起きます。
I get up at 6:30 every morning.
Analyze授業は九時に終わります。
The class ends at nine.
Analyze十二月二十四日に友達と会います。
I will meet a friend on December 24.
Analyze卒業式にこの歌を歌います。
We will sing this song at the graduation ceremony.
Analyze日曜日に部屋を掃除しました。
I cleaned my room on Sunday.
Analyze映画は何時に始まりますか。
What time does the movie start?
Analyze