Happiness (Yoshizumi Wataru)

From ShoujoLove:Akatsu-kun is a young man in love with his work partner, Kayano-san, a pretty and intelligent woman. One day, while Akatsu-kun was shopping in a little store, he saw a little boy who was reading a Playboy magazine, then, Akatsu-kun realized this little boy is Kayano-san's son!!