Nande Omae ga Ki ni Nannen!?: Rival ga Koibito ni Narimashita

Three months into their relationship, Miyako suddenly realized something. That was...
“We haven't done anything but have sex since we started dating, have we!?”
Looking back, they were only having sex every time they met. Could they really be called lovers? Miyako began to feel uneasy about his relationship with Azuma...

Note: Includes an extra chapter.