ツバキの家庭は、商社勤めの夫が海外駐在で不在のため、大学浪人中の息子と最近妻が亡くなり独り身の義父の3人暮らし。優しくてきれいだが、どちらかというと過保護気味のツバキは、最近、勉強より性に関心が強い年頃の息子と、妻が亡くなり気弱になっている義父の事が心配でならない。一方ツバキはというと夫が不在のため夜のほうは日照り続き。自慰で解消しているのが日課だった。そんなツバキは分かっていても息子や義父を異性として見てしまう。ある日、息子には勉強に集中出来ないからとオナニーを手伝ってしまい、またある日は義父に性のご奉仕をしてしまい・・・Tsubaki's husband, who works for a trading company, is away on assignment overseas, so she lives with her son, who is a university student, and her father-in-law, who is single since his wife recently passed away. Tsubaki, who is kind and beautiful but rather overprotective, is worried about her son, who is more interested in sex than in his studies, and her father-in-law, whose wife has recently passed away. Meanwhile, Tsubaki's husband is away and her nights are full of sunshine. Her daily routine is to masturbate to get rid of it. Tsubaki sees her son and father-in-law as the opposite sex, even though she knows it. One day, she helps her son masturbate because he can't concentrate on his studies, and another day, she gives sexual services to her father-in-law...