Per Wiki:

Shizuka is a rich heiress and childhood friend of the F4. She and Rui particularly are very close; she was the first person who was able to get him to come out of his shell, and the two were inseparable for much of their childhood. She began a modeling career during her high school years, but shocks everyone at her twentieth birthday party by announcing that she plans to give up her career as a model as well as her position as the Todo heiress to move to Paris and become a human rights lawyer. In the drama, Shizuka was the inspiration that convinced Makino to attend Eitoku, and later to pursue a legal career.

Rui initially accompanies Shizuka to Paris at Tsukushi's request, but their relationship suffers as Shizuka spends more and more time at work. Eventually, Rui returns to Japan in frustration. Shizuka remains in Paris and eventually marries to a lawyer there, giving her bouquet to Tsukushi.