Wagamama na Ningyo-sama

Kanan has a boyish face and gets picked on often because of his tiny figure. But, things change when his gets neighbor turns out to be...a merman, and the king on the seas at that!?! Despite the king's selfish and rude pretense, he tries to booster Kanan's self esteem. Kanan wants to thank the merman for his support, but in what way...?