The New Girl is a Big Sister (後輩はおねえさん（健全）, Kōhai wa Onee-san (Kenzen)) is the 4th episode of Blend S. The episode premiered on October 28, 2017.
The author of the dōjinshi, Miu Amano, is hired as the cafe's "big sister" archetype. She mistakes Maika and Dino for a couple, and begins using them as a basis for her dōjinshi, although she learns from Kaho that Dino's feelings are currently one-sided. Later, feedback from customers reveals that they want Maika to be more sadistic, so the others attempt to "train" her via sadistic anime, dark and violent video games, etc. This results in Maika's persona and attire turning full dominatrix. However, she is relieved when she is told to tone it back again when serving most customers, limiting this to extreme style to only those few who'd actually want it. Post-credits, Maika unintentionally "water tortures" a customer while trying to provide swift refill service.
By order of appearances: