So a while ago I asked about anywhere that may sell a triangle notebook similar to St. Germain's from the anime. My mum then made me one for my birthday!! : r/castlevania
Small Notebook Lined Softback, Pink Triangles, 80 pages, New | eBay
Triangular Notebook folds Neatly Out into Square Shape | Designs & Ideas on Dornob
The New, Improved Triangle Notebook by Tan Mavitan
The New, Improved Triangle Notebook by Tan Mavitan
Triangle Notebook
Triangle Notebook by Tan Mavitan | Book making, Bookbinding, Notebook
Triangle Notebook — ACCESSORIES -- Better Living Through Design