I found a washer fluid that leaked at the floor of the passenger seat.

It was leaked from here, between the hose and the check valve.

I covered it with waterproof tape for the time being.

It didn’t work.

I decided to replace the ckeck valve. (Genuine part number 38496-61A00)

I cut it off the end of the hose because it was stretched.

Replaced.

Then I tested and it seems OK.