Every Wednesday, Yuudai Shimaki takes a break from his university classes and part-time job to relax at a nearby park. During this time, a person dressed in a dog costume hands out balloons to children and even Shimaki. At first, Shimaki didn't want to accept the balloons, but the dog-costumed person seemed so disappointed that he changed his mind.
However, when the person attempted to give Shimaki another balloon, he politely declined. Much to Shimaki's surprise, the dog-costumed man was insistent and ended up running away after giving him the balloon. Shimaki was left alone with a balloon in his hand that had a note on it saying, "I like you."
Despite the many balloons, the person in the dog costume still feels his feelings aren't adequately expressed. These emotions have been present long before they met in the park.