When I was living with my sister, in fact, my sister and I were in a romantic relationship without my parents knowing. But this relationship is wrong. Thinking that if I get any deeper, it's dangerous... I left home as if running away, and that dangerous relationship collapsed. However, after several years, when I returned home, there was my sister, who was even cuter than before. The emotions that we had suppressed welled up, and I desperately tried to resist the desire to return to our previous relationship and intended to end with "just kisses." However, with that one kiss, the time that had stopped began to move. As if to fill the blank period until now, the two of them intensely desire each other. The sexual knowledge and bodies that they acquired as adults enable real sex different from that time, giving the best physical pleasure and dragging them into a forbidden swamp. The pure but crazy brother and sister's dangerous relationship begins again now.