initial investment
Refers to the capital or resources put in at the start of a project, business, or system.
A new business requires a large initial investment.
We introduced used equipment to keep the initial investment down.
初期費用 refers broadly to any up-front costs (fees, deposits, etc.), while 初期投資 specifically frames that spending as an investment expected to yield future returns.
initial investment cost
Compound of 初期 (early stage) and 投資 (investment).