Responses
http://www.mangago.me/read-manga/hyakunen_kesshou_mokuroku/ (I know it's not it but it's similar)
took me a while to remember
Shishunki no Iron Maiden
http://www.mangago.me/read-manga/hyakunen_kesshou_mokuroku/ (I know it's not it but it's similar)
took me a while to remember
Shishunki no Iron Maiden
Manga where at a certain age, a girl will develops crystals or something. The MC's friend got it and she's been studied by researchers