The Devil Is a Part-Timer! High School!, Vol. 2 - manga (The Devil Is a Part-Timer! High School!, 2);

Maou (aka the Devil King) and Emi (aka Emilia the Hero) have arrived from another world--and now they're in high school! Things are crazy enough already with classmate Chiho's ongoing crush on Maou, but are these kids going to be ready when a little girl shows up on Maou's doorstep and calls him "papa"?