Write the Ending for You Backwards

[Introverted male protagonist with low self-esteem x transfer student destined to tragedy | Two-way redemption | HE] On my birthday, I received a strange gift - a contract with the God of Death. I used my lifespan in exchange for a [script] that can rewrite the future at will. I rewritten my own cowardice, and my life suddenly became enlightened. Until a transfer student came to our class, a quiet girl who loved reading as much as I did. I thought this was the beginning of first love, but I didn't know it was the final chapter of Death's script. The trolley lost control and crashed into her. I didn't hesitate to cross out the tragedy in the script - she was saved. But a month later, a new "accident" came as expected. I wrote and altered frantically, racing against the invisible fate. The notebook became thinner and thinner, but I desperately found that I couldn't save her. Every rewrite just pushes her towards another doomed death. When the last page ran out, I laid her in the coffin. I thought the story was over. Until the God of Death stood in front of her and handed her my "legacy"—— Later, time resets and we meet again with memories. I became a novelist, and the first story I wrote was called: "Writing the Ending for You" (Death Contract + Death Loop + Ultimate BE? No, it's a top-level HE that goes both ways!)