Okuriboši / Kawa no nuši to no jakusoku / Katamori Gonbé (S01E109)

The Sending Star: A young, hard-working man hears that his grandmother is dying. He visits her house and sees that she is fine. On his way home, he finds himself in great peril... A promise with the master of the river: A boy is born and it is prophesied that his life will be taken by the master of the river when he turns 18. The year of his 18th birthday, a huge rain causes the river to almost flood. Gonbei the Duck Hunter: A hunter named Gonbei ties a rope around the legs of 50 ducks stuck in the water, but when it melts they fly off, dragging him towards a great adventure. (Crunchyroll)