High schooler Ganta Nakami has trouble falling asleep most nights. As a result, he is irritable at school, always searching for an opportunity to find a secluded place to doze off. On the other hand, Isaki Magari is a free spirit who is well liked by her friends, but no one is aware of her sleep disorder. She makes use of the school's abandoned astronomy club observatory as her secret sleeping bunker when she needs to get some shut-eye. As fate would have it, Nakami finds Magari napping in the observatory. When Magari discovers that she and Nakami have something in common, she offers to share her secret sleeping spot with her fellow insomniac. As the two find warmth in each other's company, the struggles they face start to become easier to confront.

At Academy Island, everything is settled through "Games" waged for a certain number of stars, with the strongest student being granted the ranking of Seven Stars. Hiroto, a transfer student, unexpectedly beats the strongest empress and becomes the pseudo-strongest in the school! A mind game of lies and bluffs begins!

A decade ago, mankind witnessed the deadly potential of weapons caused by the Great War. To avoid another catastrophe, governments worldwide have resorted to espionage to fulfill their agendas. In the Din Republic, Lily is an enthusiastic young girl who aspires to become a spy and serve her nation. However, she begins to doubt her abilities, as she struggles to perform well academically. Lily's passion is reignited when she is offered provisional graduation by joining the spy team Lamplight, which she eagerly accepts despite the enigmatic nature of the opportunity. Upon arriving at her destination, Lily is surprised to find six other girls waiting there, all of whom have faced their own academic difficulties as well. A mysterious man named Klaus soon appears and reveals they must complete an "Impossible Mission": to infiltrate the Galgad Empire after just one month of training. Although skeptical, the girls eventually agree to work together under Klaus' guidance—as this might be their only chance to prove their worth as spies.

Futaro has led five quintuplets to the point where they can graduate and pursue their own dreams. Now, finally, they had reached their final school festival. Having decided to make this occasion one to remember, Futaro searches for his feelings for the five quintuplets.