A student tries to fix a problem he accidentally caused in OZ, a digital world, while pretending to be the fiancé of his friend at her grandmother's 90th birthday.

When 17-year-old Makoto Konno gains the ability to, quite literally, "leap" backwards through time, she immediately sets about improving her grades and preventing personal mishaps. However, she soon realises that changing the past isn't as simple as it seems, and eventually, will have to rely on her new powers to shape the future of herself and her friends.