Tatami Time Machine Blues

During a scorching August in Kyoto, our protagonist and his worst friend, Ozu, are locked in a glaring contest in a four-and-a-half-tatami-mat room. Ozu has spilled Coke on the air conditioner’s remote control—the only AC in Shimogamo Yusuisuiso, their famously shabby sweatbox of an apartment building. Vengeful and despairing, our protagonist discusses countermeasures with his secret crush, the reliably blunt Akashi, when Tamura, a strange young man with a bad haircut, appears. Tamura claims to be a time traveler from 25 years in the future, and shows off the time machine he uses to travel. Our protagonist has a brilliant idea: the sweetest revenge would be to go back one day in time and retrieve the functioning remote control. His simple fix is complicated by Ozu and several others who are also eager to take a ride back in time. But in attempting to alter the past, our protagonist foresees the world's extinction. Even more troublingly, Akashi mentions she’s bringing someone to the upc