Kimihito hat einen Drohbrief bekommen: „Wenn du eine von Ihnen heiratest, bist du tot!“ Frau Smith und die Monstermädchen-WG wollen dem Absender des Schreibens eine Falle stellen.
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.
Kimihito a rendez-vous avec Smith et ses protégées essaient de savoir s'il s'agit d'un rencard en amoureux. Elles les suivent donc pour tenter d'en avoir le cœur net.
Kimihito e Smith hanno un appuntamento?! Le ragazze sfruttano i poteri di Suu per spiarlo, ma, quando questa inizia a disidratarsi, scoppia il caos. Una dopo l’altra, le ragazze capitolano. Nel frattempo, Smith e Kimihito, proseguendo con il loro appuntamento, finiscono in un love hotel!
墨須と公人が浮気デート！？モン娘たちはスーの身体を借り、監視をするが、水分不足のスーは水を求め大暴走♡ モン娘たちは次々と倒れていく。一方、場所を変え順調にデートを続ける墨須と公人は、ついにラブホテルに！？ミーアは部屋へ突入しようとするが、ラクネラに「公人の浮気現場を見る覚悟はあるのか」と問われて・・・。
ミーアと公人の水族館デートのサポート役を買ってでたメロ。気を遣ってくれるメロのおかげで、２人はとても良い雰囲気に♡ しかし、公人がイルカと戯れるメロに見とれていることに気づいたミーアは、１人でどこかへ行ってしまう。
스미스와 데이트를 하러 나간 키미히토를 보고 몬스터 아가씨들은 미행을 시작한다. 메로는 자유롭게 변신 가능한 스를 이용해 메이드 카페에 잠입하는데.
Todo indica que Kurusu y Smith están en una cita romántica, de modo que las chicas harán toda clase de maniobras por desvelar el secreto. Otro día, de visita al acuario, Miia se topa con un no-humano muy particular, que, además, parece muy interesado en ella.
