24 episodes.In the 24th episode of -Can't hide a secret--, Sang Yan checked Sang Zhi's phone and accidentally discovered that there was a person's note as "Dear" in the WeChat notes. Later, he found out that this person was Duan Jiaxu.

Can't hide a secret Sang Yan knows about the relationship between Shan Xu and Sang Zhi

Duan Jiaxu accompanied Sang Zhi home after working overtime. At this moment, Sang's mother called to inquire about the situation and asked Sang Zhi to go back and have a video chat with her.Then, Sang Yan also called. To their surprise, Sang Yan suddenly appeared in front of them the next moment.Especially seeing Sang Zhi and Duan Jiaxu walking hand in hand on campus, Sang Yan's mood completely collapsed.Sang Zhi explained carefully, but in the end Duan Jiaxu stood up, put himself behind Sang Zhi's back, and confessed their true relationship.Sang Zhi chased after Sang Yan to explain, but Sang Yan's face was still cold. He just sent her downstairs to the dormitory and forced her to go upstairs.Sang Zhi was very worried, but Duan Jiaxu also let her go upstairs.

Sang Zhi was always worried and kept looking back at Sang Yan.Sang Yan only took a few steps before he got into a fierce argument with Duan Jiaxu. Sang Yan kept attacking, but Duan Jiaxu passively suffered.Sang Yan couldn't accept all this. He knew that it was understandable that Duan Jiaxu would be with a girl younger than him, but she was his sister after all.Sang Yan finally fell silent, but anger was still burning in his heart.Sang Zhi was very worried and called him many times, but he hung up all the time.Duan JiaXu sent a timely message to appease Sang Zhi and told Sang Yan that he would always be nice to Sang Zhi.Duan Jiaxu repeatedly emphasized that he was serious, and the age gap between them was not very big, only five years old.