Jougorou Kobato has a habit of inserting himself into other people's problems. After realizing his detective skills are neither wanted nor appreciated, he makes an agreement with his shy friend Yuki Osanai to become ordinary together. Now entering high school, they aim to be perceived as regular people, yet Kobato cannot help but fall back into his deductive ways when faced with everyday mysteries. Unfortunately, mundane occurrences are not all the duo stumbles across. As they go through their school days trying to avoid drawing attention to themselves, Kobato and Osanai at times get caught up in incidents that put their plan of a peaceful, average life at risk.

Rikuo Uozumi has all but resigned himself to a bleak future, aimlessly working at a convenience store in Tokyo after graduating from college. His monotonous life is interrupted when the peculiar Haru Nonaka makes a lively appearance, frequently dropping by his workplace to befriend him. When Rikuo learns that an old college friend and crush, Shinako Morinome, has moved back into town, he reaches out to further their relationship. Unbeknownst to Rikuo however, Shinako is carrying painful memories from her past that were holding her back from accepting his feelings. Meanwhile, as Haru continually opens up to Rikuo, he discovers that she, much like him, is living by herself and wants to step out of her comfort zone into an uncertain future. The past lingers long in the mind, and the future remains elusive. At a crossroads along their intertwined paths, these three experience what it means to let go of their feelings of yesterday and embrace the change that tomorrow brings.