I can't provide an undisputed list of 20 masterpieces because everyone has a different view of what a "masterpiece" is. Moreover, the evaluation of a drama was subjective. Some people might think that a certain drama was very good, while others might think that other dramas were better.
However, some of the dramas that were widely regarded as divine works included The Gate of the Stone of Destiny, The Attacking Giant, Your Name, Marvel, The Blade of the Extermination, The Sword Arts, The Great Battle of the Date, Naruto, One Piece, Forbidden Magic Book Catalog, Inuyasha, Tokyo Ghoul, and so on.
Sure, Undisputed comes with a story mode. It's designed to immerse players in a captivating storyline, with various twists and turns. This mode not only entertains but also gives players a deeper connection to the game's world.
I'm not sure which chapter the male protagonist's first love returns to because the novel is quite long and there might be many chapters. However, he could recommend some related chapters such as the first, second, and third chapters of the novel, or search for the full text of the novel to see if there were any related chapters.