What is the word on the 4-character bookmark of Xianjian?

The front of the bookmark is the name and bust of the character, and the back is The Legend of the Sword and the Chivalrous Man.

The profile is on a piece of paper with bookmarks. The paper says, "It's better to smile back to the world of mortals, * * * I'll fly with sleeves."

Murong Ziying Age: 19 Height: 178cm Personality: cold, steady, restrained, good at fencing, casting and raising swords.

Han Lingsha Age: 17 Height: 160cm Personality: frank and generous, with clear grievances. Good at: breaking the geomantic omen of the tomb organ.

Yun Tianhe Age: 18 Height: 177cm Personality: Naturally simple, you are only good at hunting and barbecue.

Liu Age: 20 Height: 163cm Personality: smart and keen, soft on the outside and good at playing chess, painting and calligraphy.