Have you ever wanted to read CRuby's source code? Do you want to understand how Ruby works? I wrote a self-published book called “CRuby Adventures Log (CRubyのぼうけんのしょ)”. In this book, you'll read CRuby's source code alongside the author, exploring its inner workings as if on an adventure. In this talk, I'll share the essence of the book and techniques for deciphering source code that I gained through writing it.