Both series are Japanese BL dramas where the main characters already fell in love in high school but were separated and met again as working adults, finding out that they still may have had feelings for each other. Both have a serious tone.

Both BL series take place in a restaurant for a large part, have a charming chef male lead and a relaxed vibe without much drama.

Both BL series have a chef male lead and are quite simple, non-dramatic and heart-warming, good to watch when you just want to relax.

Both BL dramas have a chef main character who is charismatic and caring. Besides, none of the two series include much drama, I recommend to watch them when you want to relax.

Both BL dramas partially take place in the underworld and one of the main characters is a power bottom.

Both are Taiwanese BL dramas at least partially set in ganster environment and include a romance between two men that were kinda growing up as brothers.

Both are Taiwanese BL dramas with a romance between stepbrothers. The older brother takes care of the younger brother during childhood and later, as a result, the younger brother falls in love with him (which the older brother originally doesn't like).

Both are Japanese BL dramas adapted from a manga and include a main character that has had a sad lonely life but then another man appears, they bond over food/cooking, a romance develops between them and their lives gradually become better.

Both BL dramas include the theme of fated love from a past life and other mysterious elements - at least one of the main characters is not a regular human.

Both titles come from Japan and deal with the theme of (early) teenage love between two people of the same gender in a conservative society and the tragic consequences it can have.

Unlike Monster, Chul Soo is just a short movie with a low budget but both movies are about developing romantic feelings for somebody of the same gender during early teenage years and the pain it can cause to the involved.

The series have a completely different setting, lenghth and budget and come from different countries but both of them have a good overall quality, attractive actors and an interesting plot.

SPOILERS AHEAD (especially regarding Lovely Writer)

In both series, the main characters knew each other in childhood (when the younger boy already developed a crush on the older one) and when they are adult, the younger one appears in the life of the older one again, with the intention of making him fall for him and having a relationship with him. Paradoxically, the younger one became bigger and more confident/dominant in the adulthood, so the roles kinda reverse and the older one can no longer look down on him.