In the Outside World, only a few people know of the hidden realm called Gensokyo. Two of those individuals are Maribel Hearn and Renko Usami—the sole members of the Secret Sealing Club. Together, they dedicate themselves to learning more about Gensokyo, ranging from the Genso-Lunar War thousands of years ago to the history of the Moriya Shrine. Whether it be small talk, in-depth discussions, or tracking people who may have connections to this mystical land, even the sky cannot limit their growing curiosity.

Basara Toujou has a hard life. He is the older step-brother to two demonic sisters, Mio and Maria Naruse, whom he protects from entitled demons looking to claim Mio's power for themselves. On top of that, rising political tension within the demon realm only makes his job more difficult. When a messenger arrives with summons for Mio to the demon realm, she and her friends go in spite of the danger. Now on the enemy's turf, Basara will have to grow stronger through erotic pleasure in order to do the impossible and protect everyone.

Super deformed Hamatora.

Haruki Nakano lives an average high school life, except for the fact that his mother is overseas and he shares an apartment with his four sisters. There's the oldest, Mutsuki, who has a bad habit of falling asleep in his bed, the junior high school student Yayoi, who hits him whenever something happens, and then the grade school twins, Uzuki and Satsuki, who love to play pranks on their older brother. Stuck in a house with four girls, Haruki has to deal with all sorts of trials. From going grocery shopping, watching scary movies, to kissing practice, life is never boring in Danchigai!