পর্ব 3: Nagi এবং Ruri বিশ্ববিদ্যালয়ের একটি ল্যাবরেটরি অন্বেষণ করে এবং একটি পুরনো মানচিত্রের পাশাপাশি একটি রহস্যময় বিসমাথ ক্রিস্টাল আবিষ্কার করে।

Nagi brings Ruri to her messy graduate lab at the university, where Ruri meets Nagi's colleague Yoko. Nagi has published a paper on the unusual pyrite crystal Ruri found and listed Ruri as a co-author. In tidying up the lab, Ruri finds an otherworldly-looking bismuth crystal. Nagi shows her how it was made. Ruri also finds an old topographic map, valuable because it shows a mine not depicted on newer maps. The three girls travel to investigate. A magnet helps identify iron ore in the tailing pile. Falling into a collapsed section of tunnel, they must traverse more tunnels to escape. Nagi's ultraviolet flashlight reveals a galaxy of fluorite crystals not previously recorded. Nagi encourages Yoko to lead a study on them. (Source: Wikipedia)

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