'Romance is a Bonus Book': What is Cha Eun-ho's promise to author Kang Byeong-jun about?

'Romance is a Bonus Book' will now concentrate on the secret that Eun-ho's keeping for his professor, the celebrated author Kang Byeong-jun

                            'Romance is a Bonus Book': What is Cha Eun-ho's promise to author Kang Byeong-jun about?

Till now, Netflix show 'Romance is a Bonus Book' had concentrated on the relationship between Cha Eun-ho (Lee Jong-suk) and Kang Dan-yi (Lee Na-young).

Celebrated author Kang Byeong-jun's arc took a back seat as Eun-ho and Dan-yi got closer. Now that the two have started to date, the series will likely move on to unravel the mystery behind Eun-ho's professor and the promise that he made to him.


In the first episode, we saw Eun-ho stop his car at a particular roadway and contemplate something that he couldn't share with anyone except his boss at the publishing company. 

There were hints all along that the series is not only about Eun-ho and Dan-yi. Beginning from the interview in which Eun-ho walked out because a reporter asked a question about author Byeong-jun's retirement to Ji Seo-joon's first meeting with Eun-ho -- there was always something bigger that loomed over the series.

It wasn't until the 10th episode that we even got to meet Byeong-jun, when he was shown chained to a bed with bruises on his face. We saw Eun-ho break down after seeing his professor in that condition. 

While he calls the professor his father in a previous episode, in this one the professor's doctor friend tells Eun-ho how Byeong-jun would be happy that his student is taking such good care of his professor.

We learn that Eun-ho met Byeong-jun in the university too. Now, the series will concentrate on retelling what happened in the past. Why did the author want to retire and did he suffer from a medical condition wherein he wants others to forget him? From what we have seen, Byeong-jun requires full-time medical attention or he is prone to get hurt

Is Seo-joon, the author's son? The fact that the author's last book is titled 'April 23', which happens to be Seo-joon's birthday and the aggressive questions that he asked Eun-ho when they met for the first time has made Eun-ho wary of his decision to hide the professor.

Also, what about Dan-yi's theory? The fact that the author had decided much before the book was published that he would retire? In the coming episodes of 'Romance is a Bonus Book', we will see all of these questions being answered.

We will also see how Eun-ho's world will change once the truth comes out. Will Dan-yi understand Eun-ho's decision like he asked of her? How will their relationship be affected by this? Dan-yi has also not cut her ties off completely with Seo-joon. She likes him as a friend and the two have promised to catch up with each other often over 'udon noodles'. Will this not affect how she sees Eun-ho's decision?