To attend cram school, Sei lives in the house of his aunt Sayaka in the suburbs of Tokyo. His aunt is very plain and spends her days munching on senbei (rice crackers) and wandering around in a tacky underwear outfit. The reality of his aunt's vivid appearance was far from the 'sweet life with a beautiful aunt' that Sei had imagined, causing him to be disillusioned. However, one day, as he looked closely at his sleeping aunt, he was surprised to find that she had a surprisingly beautiful face… From then on, Sei became curious about his aunt and secretly peeked into the marital bedroom, where he saw an unexpectedly lewd side of her.
