My Girlfriend is the Man!(2018)

Nae Yeojachinguneun Sangnamja

Yun-Jae Park thought his relationship with his girlfriend, Ji-Eun, was perfect--until one shocking morning changed everything. Ji-Eun has mysteriously transformed into a man overnight! Can the two adjust to this sudden and earth-shattering change? And will Ji-Eun ever turn back to who she once was?!

(Source: WEBTOONS)

Note: Chapter count includes an epilogue.