Hiro, who has entered puberty, one day accidentally catches his parents having sex. More than the shock of seeing his parents in that way, Hiro is shocked to find himself wanting to do it with his mother, Reika. Since then, Hiro has been keeping his distance from Reika like he's in a rebellious phase. However, a "help ticket" that Hiro gave to Reika when he was young will bring the mother and son closer again. And the filial piety filled with gratitude towards his mother gradually turns into lewd filial piety...
