It Came Out, BL Manga!

BL writer Yuk-Beon (pen name) is on hiatus due to a slump when Kwon Se-Do, the protagonist of his webtoon "Neverending Tutorial," appears before him. At the same time, Park Se-Young, a student on leave from school who's been reading comics, has abandoned her exam preparations for a certification exam. Then, another protagonist from the same webtoon, Lee Jang-Won, appears before her. Suddenly entangled with the two protagonists, their daily lives begin to shift...

(Source: Lezhin, translated)

Note: Incudes one hiatus special chapter.