Lin Yühsia is the only daughter of Rat King and his successor as the godfather of Lungmen's criminal underworld. She is also a childhood friend of Ch'en and Swire. They promised to attend the same secondary school together, but Ch'en and Swire instead studied abroad in Victoria. Yühsia was disappointed that Ch'en and Swire broke their promise, which strained their friendship. Despite being the daughter of Lungmen's godfather, she has not yet decided to take her father's place. Instead, she has been working publicly as the President of the Lungmen Young Entrepreneurs' Association.
During the battle of Lungmen, Swire was being informed by Ch'en of a possible massacre in the slums and immediately called up Yühsia. Yühsia indeed confirmed about the Black Cloaks, Wei Yenwu's wetwork squad, but Swire suspected that Yühsia was involved in the demolition of the slums. In return, Yühsia told her and the L.G.D. not to interfere in this matter, saying that she was "removing those which Lungmen doesn't need."
With that being said, Swire was angry at Yusia, saying that her actions went agianst her father's will. Yühsia justified her actions due to the presence of the Reunion. At the same time, she declared she would not cooperate with either Rhodes Island or the L.G.D., believing them both dirty-handed. After that, she warned them not to come close the sewers before immediately hanging up.
Later on, Swire informed Yühsia once again of the Yeti Squadron's arrival at Lungmen. She asked for her help to fend them off but Yühsia refused. Trying to persuade her, Swire reminded her of her father's deeds and promised that Ch'en can help the Rat King end the conflict between the Lungmenites and the Infected. She also shared her future plan of turning the slums into Lungmen's downtown Districts 22 to 29. Reluctantly, Yühsia asked Swire the location of the Yeti Squadron.
Yühsia meets up with Hoshiguma and Swire at the L.G.D.. Hoshiguma is initially suspicious of Yühsia's motives but she declines having any malicious intentions. Yühsia declares that her family will never forget what 'Madame Oni' has done for them in the past, but also saying that there might never be an oppurtunity to reward her actions since Lungmen is due to collide with Chernobog. However, Swire rebuffs that statement and says that Ch'en will definitely manage to put a stop to things, before starting to cry again, murmuring about how they might never meet Ch'en again. Hoshiguma assures her that Ch'en will be alright, saying they will definitely cross paths again, to which Yühsia agrees.
Code of Brawl
Yühsia made a short cameo (as well as her first debut) when she came to the graveyard with a couple to mourn for the deceased during the Sauin. Upon leaving, they thanked her for coming along with them.
The Lin family received an invitation by Mayor Candela Sanchez of Dossoles, Bolívar, to have a vacation in the city. However, the Rat King was too old to travel while Wei was too busy with his work. Eventually, Yühsia accpected Fumizuki's request to be Lungmen's representative to Dossoles.
Upon her arrival, Yühsia was surprised to see Ch'en inside Candela's office. She was also sent by Fumizuki to Dossoles. But with the two's strained friendship, it was very hard for them to work together even though Ernesto tried to calm them down. While the two were separated, Yühsia decided to mess with an underground casino. But it all ended with Ch'en, Yühsia and Ernesto accidentally taking part in the Dossoles Warrior Championship as Team "LUNG wRATh."
Yühsia noticed that Rafaela's team was secretly implanting bombs around the city during the competion. While Ch'en wanted to report this to the mayor, Yühsia objected it because not only the mayor has allowed such crime but also it would damage her reputation as Lungmen's representative. Still, the two were in common ground in which they did not want Dossoles to fall into panic.
When the team took part in the triathlon event, Ch'en and Yühsia were betrayed by Ernesto by having them stuck inside a building. With that, the two confirmed that Ernesto was involved in the incident. The two then cooperated with each other to stop Ernesto's plan. They broke through the building and cycled towards the beach. Ch'en swam towards the cruise ship while Yühsia used Ch'en as a stepping stone and walked on the sea using her glass Arts.
On the ship, Ch'en fought aginst Ernesto and Pancho while Yühsia was investigating the situation. Yühsia also helped rescue the VIPs who were kidnapped by Pancho's men by defeating Rafaela. After everyone was evacuated, Yühsia gave Pancho and his men a "surprise" by igniting the bombs she set up in the ship.
After the incident, the relationship between Ch'en and Yühsia seemed to be fixed as Yühsia invited her to drink inside the bar she once messed with. They also regrouped with Swire and Hoshiguma and continued the summer fun. Later on, she sent back her report to the Wei family on the incident in Dossoles and also gave them a group photo on their rather messy holiday.
In the Ancient Forge movie, Yühsia appeared alongside Swire as a side character dubbed "Honor Student." During the Lunar New Year Eve, Swire and Yühsia had a chat on their entrance exam to the L.G.D. as well as Swire's investment in her business. While they watched others playing firecrackers, Swire suggested to buy some and play with it. As a person who disliked firecrackers, Yühsia diverted the topic by reminding Swire of a report she was sitting on. Swire then wanted her to promise to have a firecracker party later.
Meanwhile, the two felt the rising temperature in the midnight street. Then, they changed the topic on Ch'en staying back in the L.G.D. while the others had a day off. Swire even joked that Ch'en would be totally pissed off by that.
- The name is rendered with the Chinese naming convention, where one's surname precedes their given name.