A dazzling July day, your birthday. Into the quiet rhythm of your ordinary life, a 'confession letter' arrives. "I will wait for you today at 6 PM, in the Year 1 Class D classroom." With a pounding heart, you open the door, only to find death waiting for you. As your vision blurs to red and consciousness slips away, the morning begins anew. The looming 6 PM appointment. The relentless cycle of death. And friends whose eyes now hold a chilling difference. There's only one way to break free from this nightmare loop. Using the 'Time Travel Ring' bestowed upon you, you must rewind the mainspring of fate. "This time… I will definitely protect you." A voice echoes across time. Whose earnest vow is this?