It's my first time living together with my girlfriend, but the property I was introduced to is one that has been known to have been haunted. For some reason, my girlfriend, Sumire, liked it and we decided to live there. Since that day, I've been experiencing supernatural phenomena all around me, and I've been frightened. One day, a ghost suddenly appears. Contrary to my expectations, it's a small and cute ghost named Mahiro. Apparently, my girlfriend, Sumire, can't see him. He loves naughty things, and whenever the opportunity arises, he appears and plays naughty pranks on me... [My secret threesome that my girlfriend can't see]