That's How Many Nights We Have to Stay Over?.Aoba and Hajime are sent on an errand to buy a replacement tablet pen, only for both parties to end up forgetting their wallets. The next day, Hajime and Ko end up having a secret war over the thermostat, with Yun also getting herself involved in the hopes of losing weight. Later, Aoba hears from Hifumi and Rin about what Ko used to be like.