A self-proclaimed angel decides to intervene with a boy's love life, starting with a timer on a boy's arm, which will count down every time the boy's heart beats from interacting with his crush starting from 10. At 0, the boy will confess everything he is thinking at that moment. But it only starts there! The 'angel' has powers based on the number 10, and grand the boy the ability to stop time, make someone fall in love with him, learn who others like, and more. With comedy, romance, and drama, this is not a typical shounen series and should not be passed up.

Everyday is a normal day in the small town where Kasuga Arata lives. However, everything changed on the day of the Black Sun, and following it, a magician appears before him. The Black Sun caused the Breakdown Phenomenon which destroyed the town where he lives. Because of this, his normal life was artificially reconstructed by a Grimoire that his childhood friend had left. Just what is the purpose of the magician coming to the town? What will he do with the Grimoire's keepsake?