father's lover

Eiji comes to Tokyo to attend a seminar at a company in Tokyo, relying on his father who is working alone. When Eiji meets his father for the first time in a while at work, he is surprised to see that he has changed into a smart man. When he arrives at his father's house, Mai, his father's subordinate whom he saw at work, suddenly appears from the back room... Eiji then realizes that Mai is his father's mistress, but Eiji is also attracted to his father's urbane and beautiful mistress...