Manatsu No Mermaid

Anna is a doctor at a clinic in a small village. During one busy summer season, Sam, Anna's childhood acquaintance and rival, comes to help out at the clinic. He is now a TV-celebrity doctor, and although Anna is glad of the extra help, he can't film the clinic for his show! They can argue about absolutely anything, but she cannot let Sam know that her heart flickers with feelings of desire whenever he shows her his masculine side...
(Source: M-U)