This is a JMSDF Icebreaker Shirase challenge coin. It is a new, unopened item with a diameter of approximately 5cm. It was purchased at the general public viewing during the ship's port call in Kobe on October 11, 2025 (Reiwa 7). I haven't opened it, so I don't know the design on the back, but I suspect it's the design in the second image based on image searches, although this is not confirmed. - Model Name: JMSDF Icebreaker - Design: Ship design - Material: Metal - Condition: Unused - Size: Approximately 5cm in diameter