Himitsu Kichi de Himegoto

Having become a university student, the protagonist moved to a tranquil town. When he got used to living in a new environment, he happened to find a girl going deep into a mountain. Following after her out of curiosity he found something that looks like a building. "I-is anyone here?" This was the first encounter with Yuki-chan for the protagonist in her secret fort. Since then he has played with her using toys. One of these days, he finds a porn book hidden in her fort. It seems like Yuki-chan is interested in H things... "I'll show you my d*ck if you were interested in those things." The two's secret activities begin here...