![1girl absurdres areola_slip areolae blonde_hair blush breasts commentary covered_nipples eyebrows_visible_through_hair fate/grand_order fate_(series) hair_ribbon highres koha-ace lifted_by_self long_hair looking_at_viewer nanaya_(daaijianglin) okita_souji_(alter)_(fate) okita_souji_(fate)_(all) open_mouth red_ribbon ribbon scan shirt_lift simple_background solo rating:q score:32 post #3814457](/cdn_image/preview/47/0b/470b1f7142ffdf482d6b3029555ae5c5.jpg)
From http://typemoon.wikia.com/wiki/Koha-Ace (more info there)
Koha-Ace (コハエース) is a parody manga by Keikenchi. It stars Kohaku and features characters from various TYPE-MOON series. It is drawn in a super deformed style, and it is a self-aware series that constantly breaks the fourth wall. Carnival Phantasm included segments based on the series, and it was the focus of the 2012 April Fools' Day joke.
This tag implicates fate_(series) (learn more).