Yangqin is the young buddy and partner of main playable protagonist Sho in Crimson Sea. Originally working as a detective alongside Sho, Yangqin soon joins the IAG (Intelligence Agency of the Galaxy) to aid Sho in combating the Muton threat to Theophilus.
As the game begins, Sho and Yangqin have just returned to their office, with Yangqin complaining of their lack of funds lately, even as Sho argues that he has no intention of taking it from families who need it more, when they soon get a new client, who offers them a large reward in return for a small job she wants them to do, promising them even more if they take it so they won't be hungry again. Faced with that offer, Yangqin and Sho accept the offer, and as Sho makes his way down into the depths of Grarve to find the object the woman wanted them to find, Yangqin keeps in contact with him.
However, after Sho finds the object, he is attacked by a large slime Muton. After he defeats it, he tries to reach Yangqin, but gets no answer, before finding himself surrounded by unknown troops, along with the client, and Yangqin, who the woman was holding prisoner. It is revealed that the woman is Live D, a high-ranking commander of the IAG, and used the detective job as a cover to see if Sho was worthy of joining her organization. Since he proved himself, he and Yangqin are made the newest members of the IAG, and together, they work alongside their new teammates in Kecak, Bow Rahn, and Shami, to combat the Muton threat and save Theophilus from them.