Series by 渡辺うな

Tsubasa learns that her own life is close to ending and sets out on a trip. Her childhood friend Gin dies while protecting her, even though she was the one with little time left. Wishing to save him, she receives a mysterious clock connected to angels and demons. The clock lets her travel back through time in repeated attempts to change what happened. The early conflict follows her desperate effort to rescue Gin while facing rules she does not yet understand.