Tetotetote begins when Ai, a general office worker, Kenta, a high school student, and Mutsumi, a nail salon manager, are all hit by a truck at the same crosswalk at the same time. The next moment, the three are in a dream-like space, and are forced to make a certain decision by a loudspeaker floating in the air. In exchange for extending their remaining one-second lifespan for another 60 years, each must shake hands with the other two every day...

(Source: Natalie.mu, translated via DeepL)