OFFICIAL MIDORI NO RUUPE THREAD

Imako and Ichina are step siblings. As children, they spent a lot of time together forming an extremely close relationship. To this day, Imako wears a ring that Ichina won for her years ago. However, the siblings' special relationship extends into incestious territory. One night when the two were younger, Imako discovered Ichina's father engaging in sexual activities, and Imako and Ichina decided to experiment. Their relationship was discovered, and Ichina was forced to live on his own.

Fast forward to years later, the two are in high school and their relationship still continues on strong. However, one day Ichina discovers Imako carrying around a book about dangerous drugs. Concerned, he decides to investigate to contents of the book. While doing so, classmate Tatsuki gives Ichina a sample of one of the drugs detailed in the book. One night, Ichina finds Imako to be a bit unruly so he slips her some of the drug. This leads to Imako hunting down Tatsuki to learn about the drug he gave to Ichina. Using her interests in the drug as leverage, Tatsuki begins turning Imako into his sex slave.

Around the same time, we discover that Ichina's cat Mii has run away, Mikage notices Ichina at a makeshift grave dedicated to Mii, and eventually mentions a story of another cat, possibly a double entendre for what Ichina thinks could be happening to Imako. Ichina becomes increasingly concerned for Imako as he notices the she and Tatsuki become noticibly closer. What's more, Imako has stopped wearing Ichina's ring. Eventually, Ichina begins to break down as Imako, Tatsuki, and classmate Mikage stop showing up to school, and Ichina begins formulating twisted delusions in his mind.

(Note: The following information comes from the currently untranslated final chapter, so I'm iffy on the details)
While his downward spiral of depression continues, Ichina begins to remenisce about Imako as he gets a message from Mikage; and wastes no time in meeting her. While he and she talk, Mikage gets a call from Imako, which she lets Ichina listen in on. Ichina then rushes back home to find Imako. After some cat-ear sex the two siblings share an emotional reunion.

Some time later, Mikage runs into Ichina holding onto his cat, Mii. Mikage is incredibly startled as she presumed Mii to be dead. In the same vein as Mikage's earlier double entendre, Ichina is happy that his cat has returned. The siblings then ride off on a bicycle together, with Imako sporting a new ring.

Woohoo!! Confusing but happy ending, fuck yeah!. It was nothing but his crazy fucking imagination the whole time and that makes me so happy about the whole thing, and makes even the imaginary sequences so much hotter knowing it didn't actually happen.