have you check this out? there's a sequel to this manga:
It's titled: [sono ato no misutaa maameido] or [mister mermaid after that]
said it was published in a doujin mizushiro sensei create [sutoreinji no taiyou] or [strange sun]
here's the detail on page:
http://www.mangago.zone/read-manga/mister_mermaid/mf/v01/c004/42/
♡ Solo scanlator
♡ I now mainly pick up BL manga that were dropped by others (but not those already officially licensed in english).
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Yun#5393