![1girl :d absurdres ahoge alternate_costume bag bangs black_bow black_scarf black_skirt blush bow brown_cardigan brown_eyes brown_jacket cardigan commentary_request cowboy_shot dress_shirt eyebrows_visible_through_hair fate/grand_order fate_(series) fringe_trim grey_background hair_between_eyes hair_bow hair_ornament hairclip hand_in_pocket highres jacket koha-ace light_brown_hair long_sleeves looking_at_viewer okita_souji_(fate) okita_souji_(fate)_(all) open_mouth plaid plaid_scarf pleated_skirt round_teeth scarf school_bag shirt skirt smile solo teeth two-tone_background upper_teeth white_background white_shirt yuki_maccha_(yukimattya10) rating:s score:10 post #3660193](/cdn_image/preview/ef/45/ef45e58540831cf9ae608f0f421617bd.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).