|Eye Color||Dark Blue|
|Main Ability||Time Reversal|
|Manga Debut||Chapter 1|
Saike Kuzushiro (葛代斎下, Kuzushiro Saike) is the main protagonist of the series.
Saike is a young high schooler with a short, average built, black hairs with a blue hue and blue eyes. He usually wears a sweater over a white shirt, white pants and white sneakers.
During his visit to Nepal Saike wears a black shirt and white trousers, and switches to a thick jacket with white pants during his trek through the Himalayas.
Initially Saike is introduced as a pessimist, nihilist and anti-social person with no future dreams and prefers to keep him away from the others, with the exception of his closest friend Mikan. He even considered himself to be a worthless person who had spent countless days with no meaning at all. However, everything turned upside down after he realized his powers; at the last attempt to save Mikan's life, Saike reversed his persona after (seemingly) knowing that only with his death that Mikan can be saved. It was during this time that he also realized that he always turn a blind eye on problems he faced because he is weak, and resolves to at least change that before he dies. After he successfully saved Mikan and survives, Saike remembers that when he is a child he dreams to be a hero so he can save others, and decides to use the second chance he receives to make it happen.
As an Oracle Holder, Saike's power is Time Reversal, in which he can "rewind" the day into the moment he awakes in the morning by jumping into the Mogura Pond, resetting every occurances into what it was at the beginning of the day. This allows him to change the outcome of a specific incident as he retains his memories from the previous time. Even if he fails, he still can rewind the day as many times as he please until the desired outcome is reached, which, when combined with careful observation, allows Saike to find out his enemies' weaknesses and defeat them with ease.
According to Dr. Mutton, while Saike's power did resets his body, it does not reset his brain. As the result, overusing the power will give too much strain on Saike's brain that weakens his physical condition over time, and eventually results in death. The damage is noticeable because Saike had known to use his power countless times to save Mikan, 15 times to defeat Hizu, several times to save him later, around 227 times to defeat Ana and 10 times to defeat Sakagami, after which point Saike lost his memory, possibly after his brain was strained too much, allowing Johann to manipulate him into joining his cause. Fortunately Saike regained his memory at some point afterwards, and used his power once again to save Hizu. However, at this point Saike's body had been badly weakened to the point that according to the Kumari, he only have four days left to live.
Saike desperately tried to use his power once more after knowing that Johann had killed Hizu and Ana, and successfully recovered the Healing God. Knowing that he cannot get to Mogura Pond in time, he assumed that his power can be used in any other large, deep bodies of water, which turns out to be correct - he successfully rewinded the day by jumping into Lake Gokyo and turned the tables on Johann by foiling his plan to recover the Healing God and saving Hizu and Ana. However, their victory comes with a cost; Saike is on the verge of death after the battle.
After the Healing God cures Saike, he no longer felt the side effects of overusing his powers anymore. It seems that from this point onward he will try to use his powers efficiently to prevent his body from being damaged beyond conventional recovery again.