Okay, the user wants me to translate "quarter-circle" into Japanese. Let me think about the correct term here. A quarter-circle is a quarter of a circle, so in Japanese, that would be "四分の1円" (shibun no ichi en). Wait, but sometimes technical terms might have specific translations. Let me confirm. "Quarter" as in one-fourth is "四分の1" (shibun no ichi), and "circle" is "円" (en). So combining them, "四分の1円" seems right. I should make sure there's no alternative term. Maybe "四分円" (shibun'en) could be a possibility, but that might be more like "quarter" as in currency. Since the context here is geometry, "四分の1円" is more accurate. Alright, I'll go with that.