Who Exactly Is the Protagonist's Bottom? [Quick Transmigration]

Ye Fei was a devoted fan of pure romance novels. One day, after falling asleep while reading, he transmigrated and was tossed by the System into one pure romance novel after another.

System: "You're the male lead, but you don't know who the other male lead is. Your mission is to find him and follow the assigned romance plot through to the end."

Ye Fei: "There are so many possible guys. Can't you give me a hint?"

System: "The other male lead has a mole on his butt."

Ye Fei: "..." Great. So here's the question: how am I supposed to see the mole on his butt!?

World One: ABO Groveling Arc

World Two: Insectoid Love Triangle

World Three: Rivals to Lovers

World Four: The "Princess Consort" Runs Away While Pregnant

World Five: Mutual Pining in a Cultivation Novel

Worlds to be decided. They may well change.

Theme: To be decided