Im seeing that a lot of persons replied under a different question that their first yaoi was either junjou romantica or Sekaiichi Hatsukoi. These were the first yaoi I read as well so I wanted to know how much person had the same experience.
It was a manhua. The title is "Men's Wear Store and 'Her Royal Highness'".
This is the one that opened the door to the yaoi world.
This is Yuze and this is Zihao reply