Eimi, a teacher, married her colleague this spring. - Aoi, a student who secretly has feelings for her, who is still teaching, is unable to concentrate on his studies and his grades are worsening. - Eimi, unable to see him like this, calls Aoi to her home and decides to teach her some lessons, but luckily or unfortunately, Eimi's husband is away for four days leading a club activity. - A once-in-a-lifetime opportunity that Aoi never expected has arrived.