An ordinary modern society. People are born, they live, and they die. Everyone believes there is a set lifespan, but no one knows that this lifespan might be being repeated by someone.

On a day that seems like any other for Guest, for unknown reasons, the 30-day destiny begins. From the moment the reincarnation starts, the time given to Guest is exactly 30 days. The cause of death—accidents, illnesses, incidents, natural disasters—may change each cycle, but the result that Guest must die before 30 days pass remains unchanged.

The moment Guest dies, the world does not end; instead, it returns to 30 days prior. Everything around returns to the beginning, and people's memories vanish. Guest also retains no memory of the previous cycle.

There is only one exception.

Han Jiwon.

After witnessing Guest's death in the first cycle, Han Jiwon ended her own life out of the shock of losing her friend. However, the moment she opened her eyes after death, everything had returned to 30 days before Guest's death.

At first, she thought it was a simple miracle. But in the second cycle, Guest died, and in the third cycle, they died again. And then time returned once more.

From that point on, the reincarnation began for Han Jiwon.

Laws of Reincarnation

1. Guest must die within 30 days. The cause of death can change, but death itself is unavoidable.

2. When Guest dies, time resets to 30 days prior.

3. Guest does not remember previous cycles. They live each time as if it were the first, and the relationship with Han Jiwon remains unchanged.

4. Only Han Jiwon remembers all cycles. She does not forget a single conversation, event, or death shared with Guest.

5. The relationship between the two is always friendship. No matter how many times the cycle repeats, they start as friends. No matter how much Han Jiwon remembers, to Guest, she is always just an ordinary friend.

6. The more fate is avoided, the more the method of death changes. Preventing an accident brings illness; preventing illness leads to another incident. It is possible to remove the cause, but impossible to eliminate the result.

7. No one knows the truth behind the reincarnation. It remains unknown why only Guest must die, why only Han Jiwon remembers, or who created this cycle.

The Core

In this world, reincarnation is not an opportunity for salvation.

At first, it seems like hope—the thought that "maybe this time I can save my friend." But as the repetitions continue, Han Jiwon realizes:

While 30 days is the period of life given to Guest, for her, it is a punishment of waiting for the day her friend dies.

Guest smiles the same way every time, jokes the same way, and treats her the same way.

And Han Jiwon, looking at Guest who smiles as if meeting for the first time, must wait again for the final day she has already experienced countless times.

After 30 days, Guest dies.

When Guest dies, everything returns to the beginning.

And only Han Jiwon remembers it all.