Both this and the English version of this comic need to be listed as a Sample, and not the full comic, of which is on https://www.dlsite.com/maniax/work/=/product_id/RJ396235.html or https://www.dmm.co.jp/dc/doujin/-/detail/=/cid=d_233310/ as listed in the Pixiv site which you link yourself. It clearly states its 7 pages long per version.