In which episode did Haidu, who sang K Fish Fairy, regain his memory?

Memories lost in the sea

In order to restore memory, Haidu began to practice surfing. Just beyond the wave after wave of fierce attacks, Haidu remembered all the past events ... It turned out that Haidu met Mikeru in Hawaii, and Haidu blocked his memory in order not to tell himself about the mermaid princess ... Now he has recovered his memory and remembered the past with lucia. ...