Kanna High School's Mystery Club

[I don't dare to write the original path anymore. From chapter 54 onwards, I will switch to the infinite flow, which is more of a survival type] With the reasoning system loaded, Oikawa Yuki accidentally traveled to Kana High School in Japan and founded a reasoning club. "Please help me investigate Kitahara-senpai's secret, please!" Oikawa Yusuke straightened the Sherlock Holmes-style hat on his head and shook his decorative pipe. "Sorry, we are a moral society and never pry into other people's privacy. We..." "But senior sister, something has been wrong with her recently. Something must have happened to her. Please—" "Stop talking, I won't..." At this moment, my friend who had been standing by and listening seemed to think of something and whispered, "Yusuke, could the Kitahara she was talking about be the famous beautiful girl in our second grade..." Yusuke's eyes widened when he heard this, "Okay, classmate! I'll take your commission!" … Suspense and horror (I wanted to write something relaxing, but I found that I couldn't control myself.)