This is a coffee cup set by Yusuke Aida, known for his ceramic murals that adorn the walls of public buildings throughout Japan. Later in his career, he became the president of Tohoku University of Art and Design. His main work (if you can call it that) tends to be large-scale pieces like ceramic murals, so these coffee cups are quite rare. I believe the technique used was nerikomi (clay marbling). While there are many products with painted designs, these patterns offer a fresh perspective. Also, I've decided to lower the price today. I'm offering it for 28,000 yen. I will ensure the packaging is secure.