Well, the starting point of the Windbreaker anime in the manga isn't always fixed. It could be influenced by various factors like the director's choice or the production team's decision. Usually, it aims to capture the key elements from a relevant point in the manga.
The following novels recommended the male protagonist to wear a trench coat: " Dear Doctor Sheng,"" Dr. Xu's Hidden Black Moon,"" Dr. Nan's Road to Courting His Wife,"" Dr. Xu's Wife Is Not Waiting,"" Doctors Fall in Love at First Sight, Farewell Fall in Love,"" The Tsundere Prince Charming is a Doctor," and " The City Monster Doctor." These novels all had modern romance plots, and the male protagonist often appeared in a trench coat.