Where does “新婚旅行” come from?

新婚旅行 (Japanese) comes from Japanese 旅行, from Middle Chinese 旅行.

新婚旅行 (Japanese): a honeymoon

Definitions

Step	Language	Word	Meaning
1	Japanese	旅行	travel, a trip, a journey, a voyage, a tour; to...
2	Middle Chinese	旅行	—

新婚旅行 — Etymology, Origin & Word History | Etymology Explorer