I think I got blocked on LINE!

I don’t know all the details, but if he’s the type of man who cares about appearances, he may have felt his pride was hurt—perhaps taking your words as an indirect criticism that he was being cheap. When he asked, “Are you going to drink it all?” it might have helped if you had gently clarified what he really meant at the time. Also, when putting the ¥20,000 into his bag, it may have been better to add something apologetic and modest, like, “I was having such a good time that I got carried away and drank too much…” I’m also wondering whether he really couldn’t accept it directly from you. The fact that you returned the money, including the transportation allowance, is another point to consider. If you wanted to meet him again, returning everything—including the transportation allowance—may not have been the best move. If you treated him as though you thought he was cheap, he would have sensed that too. Blocking someone on LINE is very much a sign of the times. From my more old-fashioned perspective, I find the man’s response rather immature, especially since this was your first meeting and neither of you knew how the relationship might develop. Returning the ¥20,000 on the spot was kind, and I would sincerely appreciate the thoughtfulness. However, if you wanted to lead to a next meeting, instead of simply returning it and ending things there, you might have brought him a small thank-you gift next time, invited him somewhere in return, or suggested a restaurant and offered to split the bill up to ¥20,000. The old custom of returning a celebratory gift may feel like a bothersome tradition, but exchanging gifts can be useful for deepening a relationship. If you want to build toward another meeting, why not try applying that idea, even if only as a starting point?

If it were me, I’d reply, “Thank you very much” (lol).

It might be better to ask again once you’ve sobered up.