Technically this probably isn’t a yixing at all. This is a pot made in the style of yixing teapots with an interesting white/gray coloured clay. The construction suggests that it’s probably wheel thrown with a clay that was considerably more liquid than typical yixing clay before firing. It’s probably a good example of karamono – literally “Chinese things” but in reality often just wares made in the Chinese style. The mark is “Sōgen seisei” if read in Japanese or “Zongyuan jingzhi” in Chinese. I couldn’t find any info on the name other than in an auction catalogue from Fukuoka in 2014 that also lists a pot with the same mark and white clay. No pictures there though. 135ml.