Complex sentence: In the same incident, she is saved from a falling bookcase by Lin Koujo, who is injured instead; to repay her debt, she fills in for Lin to assist SPR's manager Kazuya Shibuya.
Split into simpler sentences: In the same incident, she is saved from a falling bookcase by Lin Koujo, who is injured instead. To repay her debt, she fills in for Lin to assist SPR's manager Kazuya Shibuya.