expression, godan verb (-ru)
get into the swing of things; warm up to; get excited by
Describes becoming absorbed in an activity, often after an initial period of hesitation or when one's mood rises to match the occasion. Commonly used when someone starts enjoying a conversation, performance, or creative work.
最初は緊張していたが、話しているうちに興が乗ってきた。
I was nervous at first, but as we talked I got into the swing of things.
彼は酒が入ると興が乗って、面白い話を始めた。
Once he had a drink, he warmed up and started telling interesting stories.