flood of customers; roaring business
A yojijukugo describing a shop or business bustling with a constant stream of customers. Often used in expressions of hope or congratulations for commercial success.
From the very first day of opening, the shop was flooded with customers, and the owner was extremely busy.
新しいカフェが千客万来で、行列ができている。
The new café is doing roaring business, with a line forming outside.