Hitozuma o Ecchi de Kudoku Houhou

The moment he first laid eyes on her, he fell in love. It was the first time in his life he had ever felt that way. Yet that love ended before it could even begin — for the one who captured his heart was none other than the mother of his best friend.

When summer vacation begins, Yuusuke is summoned by his best friend, Fujino Takayuki. Takayuki confesses that he is planning a week-long trip with his girlfriend Kasuga Satsuki — who also happens to be Yuusuke's childhood friend — but there is a problem: his mother, Fujino Kiyomi, does not approve of Satsuki. Since telling the truth would never earn permission, Takayuki lied and claimed he was traveling with Yuusuke instead. Begging on bended knee, he asks Yuusuke to play along. Reluctantly, Yuusuke agrees, little knowing that Takayuki's mother, Kiyomi, is the very woman who holds his heart.

Days later, Yuusuke's carelessness catches up with him. He runs into Kiyomi and is immediately cornered: if he was supposed to be traveling with Takayuki, why is he home? Kiyomi presses him for answers, her eyes filled with a mixture of anger and trust. Before Yuusuke can find a way out, Satsuki's older sister, Kasuga Miyo, bursts into the room with shameless declarations about "claiming Yuusuke's virginity" and openly reveals that Takayuki and Satsuki have gone off together, likely to spend the night in intimate ways. Kiyomi is horrified and demands to know their destination so she can bring her son back, but Miyo cheerfully claims ignorance.

With nowhere else to turn, Kiyomi fixes her gaze on Yuusuke, pleading for the truth. Torn between loyalty to his friend and the woman he loves, Yuusuke cannot bring himself to betray Takayuki's trust. Stunned by his refusal, Kiyomi declares that she will not leave until he talks. Miyo, delighted by the chaos, announces she will be staying over as well. Before Yuusuke can process what is happening, his home has become the stage for an unexpected sleepover.

A first love he thought had ended before it began. But perhaps it had only been waiting for the right moment to bloom. On this chaotic summer day, an impossible romance — a forbidden love between a young man and his best friend's mother — is about to awaken.

[Condensed from the official site]