Before I start I just want to explain that it is getting harder and harder to source pictures that I can use in my posts for some of the more obscure subjects, so please excuse the lack of illustrations.
In Japanese mythology, Samebito is a sea monster. Black in colour but with green eyes, Samebito was told to leave the ocean by the sea king. When he left the sea, Samebito sheltered on a bridge where he met someone called Totaro. Totaro is a hero in Japanese mythology and was fully expecting to fight the monster, but seeing Samebito looking so pathetic and sorry for himself Totaro took him home where he had a lake that the monster could live in.
Totaro had been looking for a bride and fell in love with a princess called Tamana. The problem was that Tamana's father would only allow Totaro to marry his daughter if he provided a gift of 10,000 precious jewels. Totaro didn't have this kind of wealth and became very ill with grief. When Samebito heard how ill Totaro was, he began to cry. His tears turned to precious jewels which he gave to Totaro as repayment for giving him a new home, and Totaro was able to marry his princess.
I think that's quite a nice story, and it certainly makes a change from the hero having to kill the monster to save the princess! I think there should be more stories where the monster and hero team up...