Netorare Wife Misumi - Lustful Awakening

Shoma and his wife Misumi have recently moved into their new home. In the same building also lives the cheerful and lively Chiyo, Shoma's cousin, with whom he grew up.
He does a desk job and his life goes on as usual, until one day, coming back from home, he notices a suspicious man. What will become of Shoma and his wife Misumi?