Monster Musume no Iru Nichijou - 1x09 - 脅迫状が来た日常- Followmy.tv

The girls are shocked when it appears that Kimihito is going on a date with Ms. Smith. Miia, Papi, Cerea, Mero and Suu immediately begin following them, first to a maid cafe (where Mero disguises herself as one of the maids, using Suu as a uniform), then to an arcade (where Papi is disguised as a cosplayer), then to an ice cream truck (where Miia and Cerea impersonate servers), but they fail each time. Finally, Miia follows Kimihito and Ms. Smith to a love hotel, where she meets up with Rachnera (who has been trailing them all along). Rachnera tries to sneak into Ms. Smith and Kimihito's room, but is hindered by Miia, who causes them to be grabbed by the MON Squad. Ms. Smith explains that Kimihito had received a threatening letter from someone named "D," and their "date" was actually a ploy to lure the culprit out.