ノウム・カルデアの吸血種さん (Fate/Grand Order)

When Master came to visit Yu Mei-Ren in her room, it turned into an embarrassing episode when he accidentally walked in on her while she was busy pleasing herself thinking of Xiang Yu.

Seeing Master unusually flustered after she got seen by him at an awkward moment, she decides that now was her chance to get him to expose himself to her as payback, while also intending to relieve her pent-up frustration on him, so she makes her move...

(Source: Melonbooks)