Complex sentence: For the first time in Sayuri's life, she decided to go against being strict with Kazuya and went out buying many toys and junk food which she brough to Kazuya's hospital room.
Split into simpler sentences: For the first time in Sayuri's life, she decided to discontinue being strict with Kazuya. She bought many toys and junk food which she brought to Kazuya's hospital room.