Torikago no Marriage: Hatsukoi no Tsubasa

Kanako's father died without warning and left behind a mountain of debt from the company he ran. She has no relatives to turn to—her mother died when she was a child. At her lowest point, Shingyouji Souichi, a powerful business executive who was apparently an old friend of her father's, steps in without being asked: repays the debt, restarts the business, rehires the staff, and becomes her legal guardian. He arranges for her to live not at the Shingyouji family home but in an apartment occupied by his two adult sons, and when Kanako arrives, he delivers one more piece of information: she is to choose one of them to marry, and whoever she picks will inherit his company. The cage, as it turns out, was built long before she noticed it.