Taro, the son, had a bad habit. Whenever his father was away on a business trip, he would always peek into his mother's bath. His mother noticed this, but took it lightly, thinking, "That's just what happens during adolescence." On this day, as always, when her son peeks in, his mother calls out to him, "Let's take a bath together," and invites him into the bath. Then, her son, with his penis growing, comes in shyly. Seeing this, his mother...