One Punch Man has sold 28 million copies in Japan with 27 volumes in circulation : r/OnePunchMan

One Punch Man Volume 27 Extras. From @Nan_C_the_H0BBY on Twitter

One Punch Man, PDF, Manga

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One Punch Man Volume 27 advertisement in this week's Young Jump

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Dev, Author at Anime Explained

One Punch Man sells 137k copies reaching top 3 of Oricon's weekly

One Punch Man manga has 25 million copies in circulation from

One Punch Man has sold 28 million copies in Japan with 27 volumes

Dev, Author at Anime Explained - Page 8 of 61

One-Punch Man (manga) - Anime News Network