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Artist's commentary
Slipping-out swimsuit
Intentionally written as katakana by nonco, it is open to many interpretations; 抜く can mean to slip out, but as a slang, it can also mean the act of masturbation/ejaculation; ミズ is probably short for 水着 (swimsuit) in this context. However, an alternative reading could be 温 and 水, which could be read individually as "warm/snug/cosy" and "water".