If I didn't know better I'd say this was an older Flan, but there's no real indication as to whether she's an OC or an existing character.
i would conclude it is more a heavily touhou theme influenced original since the artist only mentioned in the title "do you like blonde/dark skin ladies" and judging from his/her twitter activity it would seems his/her work does take reference or influenced by touhou characters. it is a great one tho.