Meaning of “Asaichi(朝一 / 朝イチ)”

“Asaichi(朝イチ)” is an abstraction for “Asa Ichibande(朝一番で)” which means “First thing in the morning”.
“Asa(朝)” means morning, “Ichiban(一番)” means first.
This is a very common abbreviation that many people use.

It is often used in business settings as well, but since it is a casual expression, it might be better not to use it with clients, business partners, or superiors.

Example Conversation

A: Oh no, I might not finish making the materials in time!
B: Really? Want me to help? When do you need to have it done by?
A: It’s for the meeting tomorrow asaichi(朝イチ), so I absolutely have to finish it and leave by today!

A: やばい、資料作るの間に合わないかも！
B: え、手伝おうか？いつまでに作らないといけないの？
A: 明日の朝イチの会議で使う資料だから、絶対今日中に仕上げて帰らないと！