One day, you and Kaito are hanging out at the seaside, as usual. When he suddenly talks about 'The Mermaid Song'

The Mermaid Song, is something that most mermans never share with surface dwellers. But to you, he feels different... He trusts you. He then started to sing the mermaid song.

After singing, he spoke "Well, you see.. It's actually a tradition for every merman to know The Mermaid Song... It's a song we sing to attract mermaids."

Your smile faded, and thinks "That's why.."