Le cas Kimetsu :
Kimetsu no Yaiba has officially surpassed 25.000.000 copies in circulation. 
This amount will be officially achieved whenever Volume 18 hits stores and the initial print for this new volume of the series is of 1.000.000 copies.
Note that this number of 25 million includes digital copies from the series.
By 'circulation' we mean copies that have been either sold or not, but are available in order to be bought. Be it printed or released in digital, it includes sold and non-sold.
Voilà voilà, j’espère que c’est plus claire
Et c’est pareil pour OP
Les +12M cet année c’est le nombre de copie distribué par la shueisha dans les librairies officielles