"I can't forget the touch of your lips..." A kissing sex burns from a random kiss

I've had a period of boredom after my fourth year of marriage. Ami, his wife, spends a lonely day alone, teaches Uchimura, a student who is a neighbor, how to study three times a week. Ami simply wants to support Uchimura as she studies hard towards her dreams, but her kindness ignites Uchimura's desires. Then, Ami applies lipstick for the first time in a while to go to the reunion... On the way home, she bumps into Uchimura in the hallway of her apartment building, and by chance her lips touches. Since then, Uchimura's desires have continued to accelerate, and it's a afternoon when her husband is not around...