Suansoon and Ongsa are in a relationship, but an accident occurred when Ongsa rushed to celebrate Suansoon's birthday. Wracked with guilt, Suansoon wishes to go back in time to prevent their relationship. Unexpectedly, he finds himself in the past, warning a younger Ongsa about their future, but Ongsa doesn't believe him and still pursues Suansoon. A decade later, an older Ongsa returns to convince his younger self not to avoid the accident, as Suansoon's life depends on it. Ongsa allows the accident to happen. Transported back to the past, he decides not to approach Suansoon this time, determined to change their fate. (Source: MyDramaList) ~~ Adapted from the novel "Absolute Zero Ongsa Sun" (องศาสูญ) by Salil (สลิล).